问题 问答题 简答题

亲贝选择的原则及蓄养促熟的方法是什么?

答案

参考答案:(1)亲贝选择的原则:生物学最小型以上的个体;性腺发育良好;来源尽可能广泛、防止近亲杂交;健壮、无机械损伤、不携带特异病原菌的个体。(2)亲贝蓄养促熟的基本方法:逐渐升高水温(每天0.5~1℃);投喂充足适量的饵料(单胞藻数目≥20万/ml);控制适宜的蓄养密度(根据亲贝个体大小);良好的水质是亲贝性腺发育的重要保证(一天换两次水,每次全换)。

完形填空

Ted spent seven years as a prisoner of war. There he discovered the power of    1    . For more than half of that   2   he was in isolation (隔绝). He lived for ten months in total     3    . Those ten months was the longest of his life. When they   4   with wooden boards the window of his little seven-by-seven foot cell, shutting out the light, he    5    if he was going to make it.

Ted spent hours a day exercising and thinking. But at times he felt he could do   6   but scream. Not wanting to give his    7    the satisfaction of knowing they’d    8    him, he placed clothing into his mouth to lessen the noise    9    he screamed at the top of his lungs.

One day Ted got down on the    10   and crawled (爬) under his bed. He found a hole that   11   air from the outside. As he approached the hole, he saw a    12    ray of light. Ted put his eye next to the wall and discovered a small crack in the building. It allowed him to glimpse   13   , though all he could see was a     14    piece of grass. But when he saw this, he felt a surge of joy, excitement and   15    that he hadn’t had in years. “It represented life, growth and    16    ,” he later said. It was the small hope that helped Ted    17    this nearly unbearable experience.

The human spirit is   18    . It seems to run forever    19    nothing but a faint (微弱的) hope. Without it, you have nothing. With it, nothing else   20    — even the worst conditions.

1. A. thought             B. scream            C. support               D. hope

2. A. prison                B. war                 C. time                   D. month

3. A. happiness           B. sadness            C. darkness              D. silence

4. A. strengthened         B. fixed               C. covered               D. broke

5. A. reminded            B. required            C. wondered             D. feared

6. A. something         B. nothing            C. everything            D. anything

7. A. soldiers             B. friends             C. enemy               D. army

8. A. wounded           B. quitted             C. satisfied              D. broken

9. A. till                 B. since               C. as                  D. after

10. A. window            B. floor               C. wall                D. board

11. A. let in            B. put out              C. took in             D. gave off

12. A. weak               B. soft                  C. strong               D. sharp

13. A. inside             B. outside              C. above               D. below

14. A. very               B. right                 C. specific            D. single

15. A. gratefulness      B. usefulness           C. fulfillment          D. establishment

16. A. courage         B. perseverance          C. choice              D. freedom

17. A. by              B. out                   C. over                D. through

18. A. straight         B. strong               C. lucky                D. interesting

19. A. against              B. from                  C. on                   D. over

20. A. matters         B. relates               C. changes            D. happens

选择题