我国幅员辽阔,各地各方面的差异很大,为了使教学不脱离实际,补充必要的乡土教材,贯彻的教学原则是()
A.直观性原则
B.启发性原则
C.循序渐进原则
D.理论联系实际原则
参考答案:D
函数f(x)=2sin2x的最小正周期是______.
—Did you know any French before you arrived in Washington? —Never ___ it, actually.
A.had I learned
B.have I learned
C.I learned
D.was I learning