不等式2x－4≥0的解集是____．

阅读下列短文，从每小题的三个选项中选出最佳选项。B
    Water comes from the sea, the rain and the tap. Animals, plants and human beings all need water. It is important for our daily (日常的）life. We use water to wash clothes and vegetables. We use water to cook food, make drinks, wash our face and so on. Firemen use water to put out fires. Fanners use water to grow crops. Water is useful. We mustn't waste (浪费）water. We must save water. Turn off the tap when you are brushing your teeth. Don't take a shower too long. Use the same water many times.

数列$\left\{a_n\right\}$满足$a_1=\frac{3}{2},a_{n+1}={a_n}^2-a_n+1\left(n\in N^{*}\right)$，则$m=\frac{1}{a_1}+\frac{1}{a_2}+\cdots +\frac{1}{a_{2013}}$的整数部分是（   ）

影响酶催化反应速率的因素有温度、反应物浓度、酶的浓度等．如图表示在最适温度下，某种酶的催化反应速率与反应物浓度之间的关系．有关说法正确的是（  ）

16. He hasn’t come yet. What do you think__________to him?