be able to能作謂語動詞
句子中be able to do 是謂語
be able to 是情態動詞,與後面的動詞一起構成謂語。
如:
1、He is able to swim . (主謂結構)
( 謂語:is able to swim)
他會游泳。
2、 He is able to speak English . (主謂賓結構)
( 謂語:is able to speak)
他會説英語。
詞性是動詞短語,例如:
1、I doubt they'll be able to help but it's worth a try.我不敢肯定他們能夠幫得上忙,但不妨試一試。
2、He should be able to lead a perfectly normal life.他應該能夠過上完全正常的生活。
3、I have some information you may be able to use.我有些可能對你有用的信息。
這是一個系表結構,意為“能夠做…”。例如,Finally, he was able to speak English smoothly. 終於,他能流利地説英語了。