流速计法测定水的流速时,为减少测量误差,当水深小于40cm时,采用一点法,水深大于40cm时,采用两点法。
参考答案:对
电压表是测量电路中两点间______的仪表,电压表在电路图中的符号是______.
In today’s fast changing and competitive world, to be able to learn faster and more effectively is not merely desirable; it is ________.
A.essential
B.worthwhile
C.challenging
D.sufficient