检查发电机皮带是否过松时，一般用拇指压皮带的中点，挠度为（）左右为正常。
参考答案：10～15mm
Li Keqiang, graduated from __________ Department of Economics of Peking University,was elected _________ Premier of the People's Republic of China.
A．a; the
B．/;the
C．the;/
D．the; a
