感觉挺简单，但是我错了！

斯巴达

Doctors hope that one day the body’s master cells, called stem cells, can be directed to grow in organs or tissues appropriate for transplant, use them to test drugs and potentially toxic chemicals, and may study them to gain insight into basic human biology.
A.    transplant, use them to test drugs and potentially toxic chemicals, and may study them
B.    transplant, using them to test drugs and potentially toxic chemicals, and studied
C.    transplant, used to test drugs and potentially toxic chemicals, and studied
D.    a transplant, use them for testing drugs and potentially toxic chemicals, and for studying
E.    a transplant, used to test drugs and potentially toxic chemicals, and may study them

weirui5621

答案是C吗？

gracezz

这题也栽了一把。。。没看出来平行。。。竟然选了A。。。。

yawgamoth86

答案C
can be directed....(be) used.....and (be) studied
全程省略了be