t ______ research intoheart disease and its effects on the body, we do not have adequate substitutesfor the use of animals.

____ his happy look on the face, he must havepassed the exam this time

We have been trying hard to find out the ____________of the homeless man, but without luck, no one can tell who he is.

Who do you think you’d like ____

It is that I want to go on a trip this afternoon.—Sounds great! Let’s go!