某日中午，北方某地气温由早晨的零下2℃上升了9℃，傍晚又下降了3℃，这天傍晚北方某地的气温是（ ）℃．
4
--- Where is your grandpa now?
--- He ______ newspaper in the living room.
A．read
B．is reading
C．was reading
D．reads
启动振动筛应先盘动确认正常后，（）挂合启动。
A.两次
B.一次
C.三次
D.四次
