英语语法：166 Can You Start a Sentence with “Which”（在线收听）

Grammar Girl here.

Today guest-writer Bonnie Trenga will help us talk about “which” clauses and whether it’s OK to start a sentence with one—or a new paragraph.

Incomplete Sentences

Sentences that are missing something, such as a subject or a predicate, are called incomplete sentences or sentence fragments. Although your English teachers probably scolded you for leaving out vital parts of sentences when you were writing essays, you are allowed to use sentence fragments when you want to make a point.

So you could perhaps say, “I ate all the cookies. Big mistake.” Here, “big mistake” is a sentence fragment, but it's OK because it allows you to emphasize your point. “Which” clauses that appear at the beginning of a sentence or paragraph are likewise incomplete sentences, and you are allowed to use them occasionally.

“Which” Clauses as Fragments

“Which” clauses that stand around all by themselves appear in novels and magazines all the time. You’ve probably come across a lonely “which” clause. What happened when you noticed it? It definitely stood out and you paid attention.

“Which” clauses have traditionally modified noun phrases, as in this example:

I stepped onto the train, which had finally arrived.

Here, the “which” clause--”which had finally arrived”--describes the noun “train.” If you wanted to highlight to your readers that the train was very late and you were annoyed, you could use a “which” fragment:

I stepped onto the train. Which had finally arrived.

By using a period to separate the “which” clause from what it describes, you are slowing things down and making the “which” fragment more noticeable than it would be if you kept everything together in one sentence (1). Writers have been using this technique since at least the 14th century (2).

You can also use a “which” clause to modify another clause or an entire sentence (3), as in

I had to trudge up the mountain, which tired me out.

Here, “which tired me out” refers to the entire part of the sentence that came before it: “I had to trudge up the mountain.” Again, if you want to highlight what you’re saying in the “which” clause, go ahead and make the clause its own sentence.

Sometimes a “which” fragment can start a new paragraph and modifies the entire preceding paragraph (4). Let’s say you spend one paragraph describing the details of a delicious ten-course meal you ate, and then you emphasize your gluttony by starting a new paragraph with a sentence like this “Which was why I had such a stomachache.” That’s a perfectly legitimate way to express yourself.

As you can see, “which” clauses are quite versatile. The other day I was reading a novel called The Winter Queen (5), in which some of the chapter titles were made up of standalone “which” clauses, such as “Which consists entirely of conversation.” That “which” clause referred to the entire chapter.

An Alternative to a Standalone “Which” Clause

Sometimes you might want to avoid using a “which” clause as an incomplete sentence. An easy way to achieve this is to end the sentence before the “which” clause, add a period, and then start a new sentence with “That” or another word that refers back to the previous sentence.

An example will help! Let’s consider the mountain sentence we already talked about: “I had to trudge up the mountain, which tired me out.” Instead of highlighting your aching limbs by writing “Which tired me out,” you could end the sentence with “mountain” and start a new sentence like this: “Those ten hours of exertion tired me out.”

I had to trudge up the mountain. Those ten hours of exertion tired me out.

As you can see, though, this second sentence has considerably less flair than the standalone “which” clause. It’s up to you as the writer to figure out how best to present your ideas.

Warning

I do have a warning for you about “which” clauses though: when you use one, whether it’s a fragment or part of a complete sentence, you must ensure that it’s clear what the “which” clause refers to.

If the clause could modify more than one thing, then it would be ambiguous and perhaps confusing to readers. Take this sentence: “The workers rebuilt the bridge connecting the city to its suburb, which had been destroyed during the war.” That's a less-than-ideal sentence because your clause could possibly modify three things: the bridge, the city, or its suburb. I'd guess the bridge was destroyed during the war, but the city and its suburb were probably destroyed, too. If you could rewrite the sentence, it would be a good idea to state clearly what was destroyed. Assuming it’s the bridge, I'd write,

The workers rebuilt the bridge connecting the city to its suburb. This bridge had been destroyed during the war.

You could also put the “which” clause right after “bridge”:

The workers rebuilt the bridge, which had been destroyed during the war, connecting the city to its suburb.

Summary

In summary, you are allowed to use standalone “which” clauses for dramatic effect. Be aware, though, that “which” clauses used in this manner are like hot sauce: you should use them sparingly. If you overuse the technique, it loses its dramatic effect. And also be careful so you don't write confusing sentences where your “which” clause can refer to more than one thing.