Last summer I took a course on _______.
A:how to make dresses
B:how dresses be made
C:how to be made dresses
D:how dresses to be made
阅读图,下列说法正确的是( )
如图所示,两个物体甲和乙通过细绳与弹簧连接在一起。甲重10N放住地面上;乙重5N被吊在空中,它们均保持静止。若不计弹簧及细绳的重量,弹簧受到的拉力为____,甲物体受到的合力为____.