如果持续不间断运动至少20—30分钟,则锻炼的运动强度一般控制在最大强度的()
A.20-30%
B.30-40%
C.40-50%
D.50-60%
参考答案:D
—Which would you like, tea or coffee?
—Either OK, but I prefer coffee milk.
A.is; with
B.is; to
C.are; with
D.are; to
将电压B、C、A相加于相序表A、B、C端钮时应为正相序。