阻碍多精入卵的快速反应和晚期较慢的反应各由哪两种离子引起?
参考答案:
由Na+内流和Ca2+释放。
Helen Keller was a US author and public speaker who became blind and deaf at the age of 19 months. Anne Sullivan became her teacher in 1887 and taught her to read, write, use sign language and speak. Keller received degree from Radcliffe College in 1904 and spent the rest of her life encouraging others with difficulties like hers to overcome them. Her books include The story of My Life (1902) and Out of the Dark(1913). Her life was the subject of the play The Miracle Worker
小题1:Helen Keller was an author in ________.
A.English
B.America
C.Australia
D.China小题2:When she was 19 ________ old, Helen Keller became blind and deaf.
A.days
B.years
C.months
D.seconds小题3:Did Helen Keller receive a college degree?
A.Yes, she did.
B.Yes, he did.
C.No, she didn’t.
D.No, he didn’t.小题4:Which book is written by Helen Keller?
A.The story of My Life
B.Out of the Dark
C.One million pound
D.A and B小题5:Helen Keller is a/an ________ person.
A.honest
B.hard-working
C.beautiful
D.lovely
根据短文内容,回答问题。
Look! This is a picture of our classroom. There are fifty desks and chairs in it. They are for students.
On the desks are our books. There is also a big desk in the classroom. It's for our teachers. Under the
teacher's desk, there are two basketballs and a football. We can play basketball and football after class. What other things can you see? Yes, there are two maps on the wall, a map of China and a map of the
world. Our classroom is very nice. I like it very much.
1. Is this a picture of our school?
________________________
2. How many students are there in our class?
3. Is our teacher's desk big?
4. What are under the teacher's desk?
5. What are on the wall?