题目

The National Day Parade for the 60th anniversary of the founding of China is so grand that it certainly doesn’t          the whole nation.        A．let down   B．calm down       C．break down      D．set down 答案：A如图（甲）是某物体运动的s-t图象，则图中能与之相对应的v-t图象是（ ）A．B．C．D．