Has he realized that he must study hard?yes,he studies harder than before.为什么这里用 has he realized.而不用does he realize?

Has he realized that he must study hard?yes,he studies harder than before.为什么这里用 has he realized.而不用does he realize?
Has he realized that he must study hard?yes,he studies harder than before.
为什么这里用 has he realized.而不用does he realize?

Has he realized that he must study hard?yes,he studies harder than before.为什么这里用 has he realized.而不用does he realize?
表示过去对现在的影响,故用完成时