Who should be responsible for the accident?–The boss, not the workers. They just carried out the order _____.

I’ve promised to help you and I’ll _____ my word

Some organizations have been__________ to help thepoor students in the western areas of China.

Researchers _______ to study mice from early ages but came across technical difficulties, so they weren’t sure they could expect clear results.

When will your new book ________ —Probably in December．