题目

春天来了,某池塘中的荷花枝繁叶茂,已知每一天新长出荷叶覆盖水面面积是前一天的2倍,若荷叶20天可以完全长满池塘水面,当荷叶刚好覆盖水面面积一半时,荷叶已生长了(    )A.10天          B.15天               C.19天               D.20天 答案：思路解析:荷叶覆盖水面面积y与生长时间的函数关系为y=2x,当x=20时,长满水面,所以生长19天时,布满水面一半.故选C.答案:CAlice：Good morning,Susan.Susan: Good morning,Alice. Alice：Can I come in?Susan: Sure,please.Alice: Oh,is this your room?Susan：No,it's my brother's room.Alice：Is this a television on the table?Susan：No,it isn't. It's a computer.Alice：I see. What's this in English?Susan：It's a map.Alice：How do you spell it?Susan: M-A-P, map.Alice：Can you spell it again,please?Susan: Yes. It's M-A-P.Alice：Thanks.Susan: You're welcome.(   ) 1. It is room.   A. Susan's brother's   B. Alice's brother's   C. Susan's(   ) 2. The is on the table.   A. computer   B. television   C. map(   ) 3. can spell "map".   A. Susan   B. Alice   C. Alice's brother(   ) 4. A is not in the room.   A. map   B. desk   C. table(   ) 5. spells "map" again.   A. Alice   B. Susan's brother   C. Susan