I'm the captain of our school team so with my            76. _________

fellow players we've won several games. There            77. _________

will an important game next month. But one of the        78. _________

best players in our team told me just then that he       79. _________

wouldn't play basketball once more. His parents          80. _________

asked him to spend in more time preparing for the        81. _________

college entrance examination. I feel sorry to him.       82. _________

But his parents think go to college is more important    83. _________

than playing sports and college was the only place       84. _________

for a smart boy like his son. So my friend had no        85. _________

choice. He wanted to make his parents happy.

简述民事法律行为成立的要件。