某同学进行体能训练,用了100 s时间跑上20 m高的高楼,试估算他登楼时的平均功率最接近的数值是[ ]
A.10 W
B.100 W
C.1 kW
D.10 kW
答案:B
— What is your room _____________?
— There is a desk and a chair. [ ]
A. have
B. do
C. like
石蜡切片常用的透明剂是
A.二甲苯
B.乙酸
C.乙醇
D.丙酮
E.甘油