委托贷款的借款人只能由（）以书面形式确定，不得由委托人以外的第三者指定借款人。
A.信用社
B.委托人
C.受托人
D.授权人
参考答案：B
A nurse instructs a prenatal class about the importance of doing Kegel exercises frequently. Kegel exercises help to
A. promote better breathing by strengthening the diaphragm muscle.B. maintain good perineal muscle tone by tightening the pubococcygeus muscle.C. minimize leg cramps by strengthening the calf muscles.D. prepare the mother for pushing by strengthening the abdominal muscles.
如图所示，物体A重10N，物体B重10N，A与水平桌面间的动摩擦因数μ=0.2，绳与定滑轮间的摩擦均不计，A处于静止状态，求水平拉力F的取值范围是多少？（可认为最大静摩擦力和滑动摩擦力大小相等，3=1.73）
