题干

下列关于哺乳动物胚胎发育和胚胎工程的叙述,正确的是(  )

A:体外受精完成后即可直接进行胚胎移植操作

B:胚胎干细胞具有发育全能性,它可发育成新个体

C:卵裂期胚胎细胞数目在不断增加,有机物的总量不断减少

D:通过胚胎分割产生多个相同后代的繁殖方式属于有性生殖

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答案(点此获取答案解析)

C

同类题5

Directions: After reading the passages below, fill in the blanks to make the passages coherent and grammatically correct. For the blanks with a given word, fill in each blank with the proper form. of the given word; for the other blanks, use one word that best fits each blank.

Ask helpful Hannah

Dear helpful Hannah,

I’ve got a problem with my husband, Sam. He bought a smart phone a couple of months ago and he took it on our recent ski vacation to Colorado, it was a great trip except for one problem. He has a constant urge____  for next messages; he checks his phone every five minutes! He’s so addicted to it that he just can’t stand the idea ____   there may be an important text. He can’t help checking even at inappropriate times like when we are eating in a restaurant and I am talking to him! He behaves____  any small amount of boredom can make him feel the need to check his phone even when he know he shouldn’t. The temptation to see ____  is connecting him is just too great. When I ask him to put down the phone and stop ____  (ignore) me, he say, “In a minute.” but still checks to see if____        has posted something new on the Internet. Our life ____ (interrupted). If we go somewhere and I ask him to have the phone at home, he suffers from withdrawal symptom. May this dependency on his smart phone has become more than an everyday problem.

   I recently read an article about “nomophobia,”____  is a real illness people can’t suffer from the fear of being without your phone! I am worried that Sam maybe suffering from this illness because he feels anxious if he doesn’t have his phone with him, even for a short time.

  Who would have thought that little devices like these could have brought so much trouble!                                                                                                                                     

Sick and Tired Sadie