【推荐2】The parents are _______ of the potential danger but their sons are _______ of it, so it is important for the parents to raise their son’s _______ of self-protection．(aware) (所给词的适当形式填空)

【推荐3】Join a small group bike tour for an evening of ________(explore) in the heart of Washington, D.C. （所给词的适当形式填空）

【推荐1】The ________ (complete) of this bridge highly facilitates the trips of people across the river banks. (所给词的适当形式填空)

【推荐2】Starting in the Yuan Dynasty, work on the terraces took hundreds of years, _________ its completion in the early Qing Dynasty. （用适当的词填空）

【推荐3】Starting in the Yuan Dynasty, work on the terraces took hundreds of years, until its ________ (complete) in the early Qing Dynasty. (所给词的适当形式填空)