双受精现象（　　）

选词填空

⑴Reading English ____  you to understand it. Many students never spend enough time (about 15 minutes) reading every day.   
⑵A ____ diet is very important for young students, so you can't eat too many hamburgers.
⑶Dad, what's the time? Is it time ____ now?
⑷The boy likes roller skating very much, but his father doesn’t have the time to take him to People's Square. So he often skates ____  his house.
⑸____  Miss Tian ____  Hunan or Sichuan? She eats so hot food.
⑹What is your uncle doing? He ____ his e-friends on the Internet.
⑺Sometimes she feels hungry ____ , so she eats an apple or a pear.
⑻Usually our parents____  new clothes____ us.
⑼What sports should I do to ____ ?  Swimming is the best sport.
⑽Cakes and sweets have____  sugar and are bad for your teeth.