1. Of the thousand of varieties of bird species in north America, ______ brigh
t red plumage, like the cardinal, are most often designated as state birds.
为什么不能选which have
答案是those that have
2. Only a small _____ of people took creative studies beyond secondary school
level.
答案是handful 为什么portion不行呢
3. I don’t think Tom enjoyed （helping）me study for the test.
这题请问是省略了关代that吗？ 挂号中的helping是因为前面是 enjoy 所以后面需加in
g吗？