Youcan’t play with your rabbit ______ you finish your homework.

The single invention of the computer _______ many new professions.[ ]

____ in a branch of the tree ___ a note which read"I’ll meet you at the School Gate"．

college students are willing to work in Western China after graduation ________, poor and backward as it is, more opportunities of employment are available.

It’s a lovely day today! ______ go out for awalk