—It's so late. Why not write the report tomorrow?—But I don't know _______ I can do it if not now.
A:why
B:when
C:how
D:where
如图所示.小明用一个透镜观看书上的一个英文单词,他看到了两个字母“YS”的放大的像。这个透镜是____透镜,这种透镜对光线有____作用