—Where is Tom?
— Well, he ______ you ______ here．Otherwise he would come down right now．
A．didn’t know; were B．hasn’t known; are
C．doesn’t know; are D．hadn’t known; were
He got well-prepared for the job interview, for he couldn’t risk _______ the good opportunity．
A．to lose B．losing C．to be lost D．being lost
---May I go and play with Tom this afternoon, mum?
---No．You can’t go out ______ your homework is being done．
A．until B．after C．before D．as
Can you ______ what I say? Do you need more explanation?
A．make sense of B．put an end to
C．attend to D．leave alone
It was at midnight ______ he got to his friend’s house．
A．when B．since C．that D．while
The global warming is more and more serious, for which human beings ______．
A．are blaming B．are to blame
C．are going to blame D．are to be blamed
