His advice made me happy, but ____.
Once new difficulties _____ in our new job, we should learn to use our brain to deal with it.
— There is a book on the grass. Whose book is it?— It Mike. Look, his name is on the front cover.
Only when they were put in prison and lost freedom(自由) _________ its importance.
The Internet is a very useful invention for us, ______ we can do lots of things at home.
Science and technology are developing ______ quickly that some new electronic products are out-of-date within several months.