当防、降尘措施难以使粉尘浓度降至国家标准水平以下时，应佩戴( )并加强个人卫生，注意清洗。
A．防毒面具B．防护面具C．防尘护具D．口罩
参考答案：C
用所给的单词的适当形式填空。
1. I'd like _____ (talk) about the names in China.
2. He is one of the _____ (good) players in our school.
3. She gives me her techniques for _____ (learn) English.
4. The boy always strives _____(do) everything well.
5. It's time for us _____(sing) the song.
6. _____ (not be) nervous, Kate.
D/Pat30 Days Sight与D/A at 30 Days Sight的区别是（）
A.前者30天后付款交单；后者承兑后交单，30天后付款
B.都是30天后付款交单
C.都是承兑后交单
D.付款和交单的时间都不一样
