I like watching basketball games __________ TV.[ ]

The young boy found ________ hard to finish the work alone.

When ______ comes to research into heart disease and its effects on the body, we do not have adequate substitutes for the use of animals.

It’s very friendly_ him to help me when I’m in trouble.[ ]

Have you got any books on English grammar? I want to borrow______.Yes, here you are. But you must return it by Friday.