—No. But it has been 3 years since I last here.
A:visit; come
B:visited; came
C:have visited; came
D:have visited; come
某哺乳动物体细胞在培养中能够分裂,在培养过程中将适量的3H—TdR(3H标记的胸腺嘧啶脱氧核苷)和某促进细胞分裂的药物加入到培养液中,培养一段时间,可观察和测量到( )
如图所示,点A,B,C是圆O上的三点,线段OC与线段AB交于圆内一点,若OC→=mOA→+nOB→,则( )