1. 如果感官動詞後的是V-ing作為賓語補足語，變被動時不需要加to。
如果感官動詞後的是V-pp作為賓語補足語，變被動時也不需要加to。
只有當感官動詞後的是不帶to的不定式（即所謂的動詞原形）作為賓語補足語，變被動時才需要加to。
2. 情態動詞變被動語態結構特徵：情態動詞+ be + 動詞的過去分詞
如：Young trees must be watered often. Your mistakes should be corrected right now.
The door may be locked inside.
Your homework can be handed in tomorrow.
像can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would) .都是
1. 如果感官動詞後的是V-ing作為賓語補足語，變被動時不需要加to。 如果感官動詞後的是V-pp作為賓語補足語，變被動時也不需要加to。 只有當感官動詞後的是不帶to的不定式（即所謂的動詞原形）作為賓語補足語，變被動時才需要加to。 2. 情態動詞變被動語態結構特徵：情態動詞+ be + 動詞的過去分詞 如：Young trees must be watered often. Your mistakes should be corrected right now. The door may be locked inside. Your homework can be handed in tomorrow. 像can (could), may (might), must, need, ought to, dare (dared), shall (should), will (would) .都是