锅炉水位自动调节系统一般采用三冲量自动调节系统，三冲量是指（）、（）、（）。其中主参数是（）。
参考答案：水位；给水流量；蒸汽流量；水位
Do I need __________ a stamp?[ ]
A. to put
B. puts
C. putting
If you want to make your friend not be too nervous before the final exam, you say:_______.
A． the early bird catches the worm
B． Many hands make light work
C． Too many cooks spoil the broth
D． Don’t put all your eggs in one basket
