题型:判断题 下列关于力的说法中,正确的是( )A.力不能离开施力物体和受力物体而独立存在的B.马拉车前进,马对车有拉力作用,但车对马没有拉力作用C.根据效果命名的同一名称的力,性质也一定相同D.只有两物体直接接触时才会产生力的作用 查看答案
题型:判断题 Research has been limited to ____ production profits, rather than ____ that GM foods are safe.A.increasing; make sureB.increasing; making sure C.increase; make sureD.increase; making sure 查看答案