实验时,不宜用作反应容器的是( )
利用一面墙(墙的长度不限),另三边用58m长的篱笆围成一个面积为200m2的矩形场地,求矩形的长和宽.
—She____(visit) her grandparents. She usually____(visit) them on Sundays. She____(visit) them again this Sunday.