Chocolate Grammarchips (#5)

      face5  One of our readers asked us to explain when to use that and when to use which.  



NECESSARY: something that is needed, important or required. 

TO know how to use the words that and which, you need to know what “necessary” means. (See the definition at the left, below Mr.Chips.) Here are two examples: 

 * Chocolate is wonderful, but it’s not necessary. You can live without chocolate. Water is necessary. You can’t live without water. 

 * Wings and feathers are necessary for a bird to fly. But it is not necessary for a bird to have purple feathers to fly. 


              face1Now, here’s a simple rule:

*THAT begins a group of words that are necessary. They are necessary to the meaning of the sentence.  Without the words beginning with “that,” the meaning of the sentence changes, or there is no meaning to the sentence.

     I never liked dogs that bark.

     If you leave out the words “that bark,” the meaning of the sentence changes. It loses its original meaning: I never liked dogs.  


*WHICH begins a group of words that are not necessary. They are not necessary to the meaning of the sentence. Words beginning with “which” may be interesting, but they are not necessary. Before the word “which” there is always a comma. There is either a comma (,) or a period (.) after the phrase beginning with “which”.

     Our neighbor’s cats, which love to eat cheese, are afraid of mice.

     If you leave out the words that come after “which,” the real meaning of the sentence does not change: Our neighbor’s cats are afraid of mice.



Pushok beg2 *annoying: something that makes you a little angry.

THERE are many squirrels in my yard. I named one Pooshok, the one that came to my window. [There are many squirrels in my yard, but I’m talking about just one of them: the one that came to my window.]  

     The squirrels that eat my strawberries are annoying* [Here I’m talking only about the squirrels that eat my strawberries. I’m not talking about all squirrels, just the ones that eat my strawberries.]  

     The squirrels, which eat my strawberries, are annoying! [Here I’m telling you just one thing they do. But what I’m really saying is that all squirrels are annoying. The squirrels are annoying!] 

Pushok portrait

     Pooshok was different. He was one squirrel that did not annoy me. He won my heart. He came to my window. He looked at me with his big eyes. Then he put his little paws together in front of him and promised not to eat my strawberries. 

     Pooshok was the only squirrel that tried to win my heart. [I’m telling you what made Pooshok special. Without the words, “tried to win my heart,” Pooshok would be like any other squirrel.] 

Other squirrels, which never tried to win my heart, are just grey nameless squirrels. [The meaning of the sentence does not change if we remove the “which phrase”: Other squirrels are just grey nameless squirrels.] But Pooshok was a friend with a name that didn’t eat my strawberries. §

face1Here’s the simple rule again: “that words” are necessary; “which words” are not necessary.

 ©InterestEng. July 2013  §  The stories in the magazine portion of the site are written by English language learners. Stories are corrected by a native English speaker.  § Photos are staff or used with permission.  §  To contact us: