A:①③
B:②③
C:②④
D:③④
What to Bring When Visiting Lijiang of YunnanWelcome to Lijiang. Lijiang is a nice place to visit. If you visit Lijiang, you’d better do as the following.
在“互成角度的两个力的合成”实验中,用两个弹簧测力计分别钩住细绳套,互成角度地拉橡皮条,使它伸长到某一位置O点.为了确定两个分力的大小和方向,这一步操作中必须记录的是( )