发动机是向汽车提供动力的装置.汽车在行驶时,发动机把油料中的____能转化为内能,再转化成机械能.如图所示为此四冲程发动机装置工作时的____冲程,此冲程气缸内气体的温度____(“升高”、“不变”、“降低”).
在下图中,①是地表径流,②、③是地下径流。读图完成问题。
relaxing, on, hour, useful, an, and, finish, from, favorite, after
Dear Jack,
I am very busy____Friday. At 8:00 I have math. It is not fun. The teacher says it is____ but I think it is difficult.____ that, I have P.E. at 11:00. It is easy____fun. Lunch is____12:00 to 1:00. I have Chinese at 1:20. It is my____subject. My classes____at 2:00, but then I have____art lesson for two____. It is really____.
How about you?
Yours,
Lucy