A survey of the opinions of the students _______ that two hours of physical exercise a day _______ acceptable in our campus.
A:shows; are
B:shows; is
C:show; is
D:show; are
小数部分最大的计数单位是____,整数部分最小的计数单位是____,它们之间的进率是____。
已知tanα=2,计算
① 2cos(π2+α)−cos(π−α)sin(π2−α)−3sin(π+α)
② sin3α−cosαsin3α+2cosα .