sandstorm ________ Beijing several times in the last few years.
问题描述：
sandstorm ________ Beijing several times in the last few years.
用 HIT 的正确形式填空
Kitty will believe it when she has seen it with her own eyes.（保持句意不变）
Kitty ______________ believe it _____________she has seen it with her own eyes.
Did they know the answer to the question?I don`t know.(合并为复合句)
I don`t know _______________ they ______________ the answer to the question.
答
has hitfor/in/during+the past/last+一段时间,多与现在完成时或现在完成进行时连用.根据语境事情是发生完了,不是发生了并仍继续,所以用现在完成时.won't until （not ...until句型,直到...才...）whether/if knew (...