It is a golden rule in international trade that if you export nothing but raw materials, you’re at the ________ of world prices.

下列各句中，没有语病的一句是(　　)

Could you tell me when________ inBangkok —Sorry, I don’t know. I even want to knowwhat to do when ________.

单项选择（每题1分）Is this the reason _____ she explained in the report for her success in the job?

Not easy as the problem of pollution is ____, no one should just stop trying.[ ]