问题
选择题
Danny is playing ___ and Tom is playing ___ . [ ]
A. piano, football
B. a piano, a football
C. piano, the football
D. the piano, football
答案
答案：D
搜题请搜索小程序“爱下问搜题”
Danny is playing ___ and Tom is playing ___ . [ ]
A. piano, football
B. a piano, a football
C. piano, the football
D. the piano, football
答案：D
完成下列实验报告：
| 实验步骤和方法 | 观察到的现象 | 分析原因 |
| 步骤1：（1）利用排水法采集两瓶人体呼出的气体 （2）用玻璃片盖好两瓶空气． |
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| 步骤2：分别向一瓶人体呼出的气体和一瓶空气滴入数滴石灰水，并且振荡． | ______ | ______ |
| 步骤3：将燃着的小木条分别插入一瓶人体呼出的气体和一瓶空气． | ______ | ______ |
| 步骤4：取两块干燥洁净的玻璃片，向其中一块吹气，并与另一块对比． | ______ | ______ |
