Bob and Mike are good friends. They are in the same school, 1 in different classes. Their favorite2s Chinese. They think it is very 3. They go to school on weekdays. They come to school48:00 in the morning. Today is Thursday. Bob and Mike are having classes in their classrooms.

   Now Bob is5 an English class. He is speaking English with his English teacher Miss Sun. She thinks Bob speaks English very 6. Mike is having a Chinese class.7teacher is talking about Beijing Opera with the students. He is looking at the teacher and listening carefully.

   Their last class is at 4 o’clock. After class they go to the playground to do sports. Bob usually 8 in the playground and he is good at running. Mike likes playing basketball with his other9 . But he sometimes watches Bob run there. After doing sports, they usually 10together* because Bob’s house is near Mike’s house.

①氨基酸    ②C，H，O，N等元素   ③氨基酸分子相互结合    ④多肽    ⑤形成一定的空间结构．