— ________. I have another one at home.
A:It doesn't matter
B:You're welcome.
C:My pleasure
D:It's too bad
在观察装片时,由低倍镜换成高倍镜,细胞大小、细胞数目、视野亮度的变化()
一个实数a的相反数是5,则a等于()
跳水运动员从10m高的跳台上跳下(不计阻力),在下落的过程中( )