A:营养生殖
B:分裂生殖
C:出芽生殖
D:孢子生殖
There isn't any difference between the two. I really don't know _______.
“x<2”是“x<1”的____条件.(从“充分不必要”、“必要不充分”、“充要”和“既不充分又不必要”中,选出适当的一种填空)