单项选择题

According to the passage, the primary benefit of the new research is that ______.

A．scientists can study the pituitary gland for the first time
B．the procedures are simpler and require fewer laboratory animals
C．the study of intact laboratory animals has now been rendered obsolete
D．researchers were able to discover prolactin

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热门试题

单项选择题

According to the passage, Chlamydia causes infertility in women by ______.

A．causing tissue changes which block the oviduct
B．shrinking and swelling tissues in conjunction with the menstrual cycle
C．allowing skin tissue to encyst reproductive tissue
D．necessitating abdominal surgery to remove damaged tissue

单项选择题

All of the following are true of the transplantation technique EXCEPT that ______.

A．it avoids the need for subjecting a laboratory subject to repeated major surgery
B．it permits scientists to monitor changes frequently
C．the transplanted cells grow as they would in their normal site
D．the transplanted cells can be easily grown in vitro