题目选项分析

Doctors hope that one day the body's master cells, called stem cells, can be directed to grow in organs or tissues appropriate for a transplant, used to test drugs and potentially toxic chemicals, and may study them to gain insight into basic human biology.

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, used to test drugs and potentially toxic chemicals, and studied to gain insight into basic human biology.