如图，将△ABC水平向右平移了acm后，得到△A'B'C'，已知BC=6cm，B C'=17cm，那么a=____cm．

阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。

One day an ant was drinking at a small stream and fell in. She made all efforts ____ (reach) the side, but made no progress at all. The poor ____ (tire) ant was still bravely doing her best when a dove saw her. Moved by her ____ (determine) and perseverance, the bird threw her a blade of grass, ____supported her like a raft, and thus the ant reached the bank again. While she was resting and drying ____ (she) in the grass, she ____ (hear) a man come near. He was walking along barefooted ____ a gun in his hand. As soon as he saw the dove, he wished to kill it. He would certainly have done so, but the ant bit him in the foot just as he raised his gun to fire. He stopped to see ____ had bitten him, and  the  dove ____(immediate) flew away.  It  was  an  animal  much ____(weak) that had saved her life.

王磊的父母长期在外地工作，王磊跟着爷爷奶奶在农村生活，故普通话不太标准。来到城里后，王磊意识到自己的缺点，于是天天对着镜子练习，上课积极举手发言……经过辛勤努力，王磊终于也说出标准的普通话。由此可见（    ）

①自强的人勇于战胜自己的弱点，战胜自我，超越自我  ②自强可以让我们更自信③要自强必须与爷爷奶奶在一起  ④只有有弱点的人才有自立自强的品德