Do you know the song Where has the time gone (《时间去哪儿了》）—Sure. It _______ beautiful. I like it a lot.

We find ________ hard to do a job very well.

The hotel ____ they are staying is not very far from the beach. [ ]

Scientists and doctors across the world have done _____ research over the years, hoping to find a cure for cancer.

依次填入下面一段文字横线处的语句，衔接最恰当的一组是（ ）玉树藏族自治州________，________，_________，________，_________，__________，玉树既是“三江源头”，也是“藏獒之乡”和“虫草之乡”。①东南与四川省甘孜藏族自治州毗连②是长江落差最大的标志点③与海西蒙古族藏族自治州、果洛藏族自治州等地相通④平均海拔4000米，最高点6621米⑤位于青藏高原腹地，青海省南部⑥气候高寒