SAT语法题1.designed by seattle architect james cutler,these inn

SAT语法题
1.designed by seattle architect james cutler,these innovative dwelling are sensitive to thier natural setting,【"they complement"】 the wooded outlines of the landscape
答案是complementing 我选了also they complement 请问这类句子应该怎么分析 简化之后变成什么?
2.that there 【exist】 an infinite number of worlds outside our solar system 【were】 first hypothesized by the sixteenth-century philosopher Giordano Bruno.
我理解were要变成was 但是这句的exist不用变成exists吗 an infinite number不是单数吗?
3.The panda,【whose】 chinese name means "bear cat",resembles the cat in its ability of contorting its body into various shapes
请问指代动物可以用whose吗?