为保证感染组织中有效浓度,血药浓度应该达到()
A.致病细菌的MIC
B.致病细菌MIC2倍以上
C.致病细菌MIC3倍以上
D.致病细菌MIC4倍以上
E.以上均不是
参考答案:B
It is true that knowledge _____ rather than being taught. [ ]
A. learns
B. learned
C. is learned
D. was learned
重量G=100N的物体置于水平面上,给物体施加一个与水平方向成θ=30°的拉力F,F=20N,物体仍处于静止状态,求:
(1)地面对物体的静摩擦力;
(2)物体对地面的压力。