如果对某DNA分子进行标记,此DNA分子连续复制四次,那么第四次复制后的DNA中,含有标记链的DNA占 [ ]
A.1/16
B.1/8
C.1/4
D.1/2
答案:B
Every student as well as teachers who ____ to visit the museum_____ asked to be at the school gate on time.
A.is; is
B.are; are
C.is; are
D.are; is
A.茯苓 B.附子 C.白术 D.甘草 E.人参