【推荐1】他提出了关于学生是否应该使用手机的看法。(whether)
He brought up his opinion ________________ students should use mobile phones.

【推荐3】因为被新的语言和不熟悉的环境困扰,我写信询问你能否就如何适应国外生活给我一些建议。(whether; advice)
Troubled by the new language and the unfamiliar surroundings, I’m writing to ask ________the life abroad.

【推荐3】尽管时间有限，但现在处理这个问题还不算太晚。(although)
It’s not too late to deal with the problem now, ________________________.

【推荐1】If it were not for dust, there would be no drops. (同义句转换)
________ ________for dust, there would be no drops.

【推荐2】When they were asked who had broken the vase，the children all kept silent. (同义句转换)
→________，the children all kept silent.