CTL
参考答案:
细胞毒性T细胞,在病毒或胞内寄生菌感染时,CTL可通过其TCR识别被微生物感染的靶细胞,通过细胞裂解和凋亡以及释放某些因子等机制杀伤靶细胞。
. ________ is no doubt that your world is becoming smaller, due to the technological advance made by the computer.
A.There
B.It
C.That
D.This
_____ has Simon visited the Great Wall when he stays in China? [ ]
A. How often
B. How many times
C. How soon
D. How long