It's summer holidays. For Jacob, it means having a lot of free time to play with  ____ (he) friends. Usually, he isn't so excited about it, ____ (连词) this summer is different. This summer, he is going to see Justin Timberlake — one of his favourite singers

    Jacob got four tickets to Justin Timberlake's concert after he ____（win) an online singing completion （比赛） ____. (see) Justin Timberlake is one of his dreams (梦想), so it will something he will never forget.

    The biggest problem he had was  trying ____(choose) just three friends to go with him. He ____ (wish) that all his friends could go. He asked his mother ____(介词) help. She told him to choose people who also liked Justin Timberlake. Jacob thought it was ____ (冠词) good idea, so he chose three friends who liked Justin Timberlake as much as he did. He felt sorry for not____(take) his best friend Andrew, but he knew that Andrew didn't like Justin Timberlake' s music that much. Jacob's three friends were all very excited when he ____ (tell) them the good news.

    Now the concert is just a week away and Jacob can't wait any longer.

近视眼可以配戴____矫正．

周期为2s的简谐运动,在半分钟内通过的路程是60cm,则在此时间内振子经过平衡位置的次数和振子的振幅分别为(　　)

函数$y=a^{x-2}+{\log }_a(x-1)+1$（a＞0，a≠1）的图象必经过定点 （　 　）

科学家成功地把人的抗病毒干扰素基因植入烟草细胞中的DNA分子上，使烟草获得了抗病毒能力，这个事实说明，DNA上控制生物性状的基因单位是____．