– Do you know the West Lake in Hangzhou?

– Yes, this is the third time that I ____ this beautiful city.

A．visit

B．visited

C．have visited

D．had visited

各种收缩时产生张力大小的顺序依次为

A．等长收缩＞向心性收缩＞离心性收缩

B．离心性收缩＞等长收缩＞向心性收缩

C．向心性收缩＞等长收缩＞离心性收缩

D．向心性收缩＞离心性收缩＞等长收缩

E．离心性收缩＞向心性收缩＞等长收缩