小明用天平、量筒和水(ρ水=1.0g/cm3)等器材测干燥软木塞(具有吸水性)的密度时,进行了下列操作:
①用调好的天平测出软木塞的质量m1;
②将适量的水倒入量筒中,读出水面对应的示数V1;
③用细铁丝将软木塞浸没在装有水的量筒中,过段时间后,读出水面对应的示数V2;
④将软木塞从量筒中取出,直接放在调好的天平托盘上测出其质量m2.
如图4所示的是从平面镜中看到的钟面虚象,则实际时间是( )
I have been to the Country Park many times. I think the Country Park is a b____ place for people to v____. There is a big l____ in the Country Park. We can go boating there. We always have a good t____ in the park. There are a lot of nice b____ in the park. They fly in the park and s____ in the park. How beautifully they can sing.
观察下图,1975—1982(X轴以下部分)年美国经济的状况,出现的直接原因是( )