干粉灭火剂灭火的主要机理是（）。 A.降低氧浓度 B.降低温度 C.化学抑制 D.降
题型：单项选择题
问题：
干粉灭火剂灭火的主要机理是（）。
A.降低氧浓度
B.降低温度
C.化学抑制
D.降低氧浓度和冷却
题型：单项选择题
It’s great fun to explore new places—it feels like an adventure, even when you know you’re not the first to have been there. But make sure not to get lost or waste time going round in circles.
·Do the map reading if you’re being driven somewhere. It’ll be easier if you keep turning the map so it follows the direction you’re traveling in. Keep looking 
ahead so that you can give the driver lots of warning before having to make a turn, or you’ll have to move to the back seat.
·Get a group of friends together and go exploring. You’ll need a good map, a compass(指南针), a raincoat, a cellphone to call for help in case you get lost, and a bit of spare cash for emergencies. Tell someone where you’re going before you set out and let them know what time you expect to be back. The test is not in getting lost, not in seeing how fast you can go, so always stick together, waiting for slower friends to catch up.
See if your school or a club organizes orienteering(越野识途比赛) activities, in which you need a map and a compass to find your way. This can be done as a sport, with teams trying to find the way from A to B (and B to C, etc) in the fastest time, or simply as a spare-time activity. Either way, it’s not only good fun, but a great way to keep fit.
小题1: Sitting beside the driver, you should _______.
A．direct the driver when necessary
B．look ahead to see where there’s a turn
C．move to the back seat if feeling uncomfortable
D．Keep looking at the map to find a place to go to小题2: Why do you need to tell someone your exploration plan before setting out?
A．To get information when in danger.
B．To be saved in case of an accident.
C．To share the fun with him/her in exploration.
D．To tell him/her what’s going on with the group members.小题3: Orienteering activities can _______.
A．make people work fast
B．help people stay healthy
C．help people organize other activities
D．make people get prepared for sports.小题4: The
text mainly talks about _____.
A．the fun of exploration
B．what to bring for exploration
C．the way to use a map in exploration
D．how to prevent getting lost in exploration.
