问题
单项选择题
太空中宇宙飞船上水平放置一株幼苗，若干天后，根、茎生长方向是（）
A．根向下生长，茎向上生长
B．根向下生长，茎向下生长
C．根向水平方向生长，茎向上生长
D．根和茎都向水平方向生长
答案
参考答案：D
解析：太空处于失重状态，重力对生长素没有影响，又没有单侧光照射，生长素浓度均匀分布，所以应该是一直水平方向生长。考点：生长素的生理作用。
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太空中宇宙飞船上水平放置一株幼苗，若干天后，根、茎生长方向是（）
A．根向下生长，茎向上生长
B．根向下生长，茎向下生长
C．根向水平方向生长，茎向上生长
D．根和茎都向水平方向生长
参考答案：D
解析：太空处于失重状态，重力对生长素没有影响，又没有单侧光照射，生长素浓度均匀分布，所以应该是一直水平方向生长。考点：生长素的生理作用。
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| Dear Xiaohua, Thanks for your letter. Your 1 life is really interesting I 2 I can go to visit you soon. Now I would like to tell you something 3 my life at school in Australia. We go to school five days a week from 4 to Friday. Classes 5 at nine. After fifty minutes, there is a short rest. 6 _ this time, we can eat some food in the dining hall or play sports outside. It's 7 . We have lunch at school. The food there is delicious. Classes end at 3:30 in the 8 and then we can have fun at all kinds of clubs. I know Chinese students usually have a lot of homework 9 every day. We also have homework, but it isn't too 10 . Best wishes ! yours, John | |||
| ( )1. A. vacation ( )2. A. hope ( )3. A. with ( )4. A. Tuesday ( )5. A. start ( )6. A. With ( )7. A. boring ( )8. A. afternoon ( )9. A. do ( )10. A. little | B. school B. want B. to B. Monday B. started B. On B. relaxing B. morning B. does B. much | C. family C. enjoy C. at C. Thursday C. starting C. During C. tired C. evening C. to do C. many | D. home D. like D. about D. Wednesday D. starts D. From D. sad D. noon D. doing D. few |