问题补充：
Yao Ming, who the Houston Rockets, is working hard to make his dream come true.
A. joined
B. joined in
C. took part in
D. competed in
答案：
(答案→)A. joined
B. joined in
C. took part in
D. competed in
解析：考查动词。句中join为加入之意，表示加入某一组织或团体，并且成为其中的一员，故选A。句意：姚明，加入休斯顿火箭队，非常勤奋使他的梦想成为现实。
