1.In jazz music, a riff is a simple melodic figure,------and repeated several times.

(A) usually one or two measures lasted

(B) lasted one measure or two usually

(C) is lasting one or two measures usually

(D) usually lasting one or two measures

为何选（D）不选（A）或（B），lasting和 repeated 怎能用and并列呢？

2.At its center, the sun has a density of over a hundred times ------ and a temperature of 10 to 20 million degrees centigrade.

(A) that of water

(B) of water

(C) than that of water

(D) water

为何选（A）不选(C),times 在这不是比较吗,为何不用than,那times 是怎么个用法？

请大虾指教，谢了。

many thanks !!!!