一般身体训练是专项身体训练的()。
A、途径;
B、方法;
C、手段;
D、基础。
参考答案:D
The great chance he has been looking forward to _______ at last.
A.appear
B.appearing
C.has appeared
D.appeared
一新月形薄透镜,折射率1.5,前表面曲率半径为50cm,后表面曲率半径20cm,则透镜的屈光力为()
A.+1.50D
B.-1.50D
C.+3.50D
D.-3.50D
E.-2.00D