大型玻璃钢储罐现场施工时，需根据天气变化情况，测试树脂的（）时间，及时对配比进行调整。
参考答案：凝胶
薄板的重心位置可以用悬挂法求出．如图所示，先在A点把物体悬挂起来，作出直线AB，然后在D点把物体悬挂起来，作出直线DE，即可知重心在两直线AB、DE交点C处，其实验原理是______．
Not only ____interested in a football but ____beginning to care about it.
A．the father is ,his family are
B．.the father is , ishis family
C．is the father ,his family are
D．is the father is ,his family is
