Radiocarbon dating of fossils taken from caves on islands along southeastern Alaska’s coast suggest that at least a portion of the area was remaining ice-free during the last ice age. A.suggest that at least a portion of the area was remaining B.suggest at least a portion of the area remaining C.suggests that at least a portion of the area remained D.suggests at least a portion of the area that had remained E.suggests at least a portion of the area to have remained 本题答案C，但是我有两个疑问： 1. during the last ice age是完成时的标志啊，为什么不用完成时？ 2. Suggest that不是后面用虚拟语气的嘛？为什么可以用remained
