When will the Greens arrive _______ Nanjing.
| A．at | B．in | C．on | D．to |
We can’t fix this machine well. Can you show us ___?
| A．how to do | B．what to do it | C．how to do it | D．where to do |
Did you see them ____ basketball this morning?
| A．playing | B．were playing | C．to play | D．are playing |
He didn’t study hard, so he was afraid ______ in the exam.
| A．fail | B．to fail | C．failing | D．failed |
I had some problems _____ my homework.
| A．to finish | B．finishing | C．finishes | D．finish |
Can you learn English ________ chatting on the Internet?
| A．in | B．with | C．by | D．for |