问题
选择题
Last week I met my old friend Li Ming but I forgot _____ him for his telephone number.[ ]
A. ask
B. asking
C. and ask
D. to ask
答案
答案：D
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Last week I met my old friend Li Ming but I forgot _____ him for his telephone number.[ ]
A. ask
B. asking
C. and ask
D. to ask
答案：D
、质量m ="1.0kg" 的带电滑块A，A和B之间的动摩擦因数μ=0.80．在车的左边距车S = 0.20m处有一场强
、方向水平向右的匀强电场区，电场区的水平宽度d =0.21m．现对小车B施加一个大小为10N、方向水平向左的恒力F使小车向左加速运动．已知滑块A离开电场区时，恰好脱离小车．设整个运动过程滑块A所带电荷量保持不变，小车不带电，重力加速度g =10m/s2．求：