天气现象的突出特点是（ ）
A．稳定
B．多变
C．表现为冷热
D．表现为风雨过程
天气是指某个地方的大气层在短时间内的具体状况，其特点多变．
故选：B．
The boy, ________ with his school work every day, felt rather tired and wanted to have a whole day to relax.
A．occupying
B．having occupied
C．occupied
D．being occupied
如何防止挖掘机破碎作业时触电伤人？
