嘌呤核苷酸的抗代谢物是()
A.5-氟尿嘧啶(5-FU)
B.6-巯基嘌呤(6MP)
C.次黄嘌呤核苷酸(IMP)
D.β-丙氨酸
E.尿酸
参考答案:B
The fisherman ________ the VCD since yesterday. [ ]
A. have had
B. has bought
C. has had
电力线载波机的主要技术指标及作用是什么?