如图4所示，质量为M的木板放在倾角为θ的光滑斜面上，质量为m的人在木板上跑，假如脚与板接触处不打滑.（1）要保持木板相对斜面静止，人应以多大
某种富含乳酸亚铁的口服液可以比较有效地治疗人类缺铁性贫血，这是因为其中的Fe2+进入人体后能（ ） A．调节血液的酸碱平衡
Before going outside in the morning, many of us check a window thermometer(温度计)for the temperature. This helps us decide what to wear. __36__ We want our food to be a certain coldness in
从离地H高处自由下落小球a，同时在它正下方H让以速度V0竖直上抛另一小球b，不计空气阻力，有 （ ）
__________ full preparations, we decided to put off the meeting till next week. A. We did not make B. Having not made C. We had not made D. Not
— She _____ her mom. A. looks like B. look like C. look the same D. looks the same
我国现存最早最完整的农书是（ ） A、《石氏星表》 B、《齐民要术》 C、《农书》 D、《农政全书》
If you _____ your demand, then maybe you will have more chance of getting what you want. A. conduct B. dismiss C. grant D. moderate
的直线经过点
，直线的一般式方程是 ▲ ．
