A:held u
B:turned dow
C:broke u
D:pulled dow
—How did your uncle learn to play the guitar?
—By _______.
我国婚姻法规定:直系血亲和三代以内旁系血亲之间禁止结婚,其科学道理是( )
我国以城市为重点的经济改革全面展开开始于( )