answers.

Many challenges must be overcome_____(1)___(连词) "cloned organ" transplants become reality. More effective technologies for creating human embryos, harvesting stem cells, and producing organs____(2)_____(介词) stem cells would have to be ___(3)_____ (develop). In 2001, scientists with the biotechnology company Advanced Cell Technology (ACT) reported_____(4___(连词) they had cloned the first human embryos; however, the only embryo to survive the cloning process stopped developing___(5)____ (介词) dividing into six cells. In February 2002, scientists with the same biotech company reported that they had ___(6)_____(success) transplanted kidney-like organs into cows. The team of researchers created ___(7)___(冠词)_cloned cow embryo by removing the DNA from an egg cell and then injecting the DNA from the skin cell of the donor cow's ear. Since little is _____(8)____(短语动词)manipulating ( 控制) embryonic stem cells from cows, the scientists let the___(9)_____(clone) embryos develop into fetuses. The scientists then harvested fetal tissue from the clones and transplanted it into the donor cow. In the three months of observation ___(10)_____the transplant, no sign of immune rejection was observed in the transplant recipient.

Suggested Answers:

(1) before (2) from (3) developed (4) that. (5) after

　　　(6) successfully (7) a (8) known about (9) cloned (10) following

Step 3. Homework

1. Ask Ss to review the language points in this period.

2. Ask Ss to finish the following exercises.

(1) Ask Ss to use "happen, occur, befall, take place, come about" to fill the following blanks.

　　① When did the accident_________?

　　② Our school sports meeting will ________ next week.

　　③ How did the quarrel __________ ?

　　④ It ________ to me that Mary knew him very well.

　　⑤ He ________ to be out when I called.

　　⑥ Bad luck and ill health ____on them through out his life.

Suggested Answers:

① happen ② take place ③ come about ④ occurred

⑤ happened ⑥ befell

(2) Ask Ss to use "raise" or "rise" to fill the following blanks:

① The Chinese people have ________ to their feet.

② Heavy rains ________the river stage.

③ The government is trying to ________ the living standard of the working people.

④ His voice ________ in excitement.

⑤ The wind is ________.

⑥ Where was he _______?

Suggested Answers:

① risen ② raised ③ raise ④ rose ⑤ rising ⑥ raised

Period 3 Learning about Language (2)

Teaching Goals: