Mr.White ____________(代表)himself as an expert in protecting environment.
During the course of history，many____________(协议)have been made between France and England.
If global warming continues，more and more species of land plants and animals are becoming ____________(灭绝的)．
The legal speed ____________(有限的)within the city is 35 miles per hour.
Faced with these____________(吓人的)findings，we should take measures to protect our environment.
如果你不带雨衣出去，你就要冒淋湿的危险，因为可能下雨。
If you go out __________ a raincoat you risk __________（get） wet, because it may rain.
我认为他住在那里，但我不敢肯定。
I think he lives there but I couldn't say __________ __________.
A surgeon is a doctor who does __________（外科手术）.
The fuel that pa machine provides the energy that the machine needs in order to work.
He has a good __________（掌握，精通）of English.