If 嘅sentence 叫 conditional sentence, 分左 4 種
Type 0. 當講緊事實
If (present tense), (present tense)
If I mix yellow with blue, it turns green.
Type 1. 當係講緊一件好有可能發生嘅事
If (present tense), will + infinitive
If it rains tomorrow, I will cancel the picnic.
Type 2. 當件事係好細機會發生/冇可能
If (past tense), would + infinitive
If I were you, I would break up with him.
Type 3. 講緊過去/你後悔嘅事
If (past perfect tense), would have + past participle
If I had not killed a man, I would have been free now.
當講一啲冇可能發生嘅野, 就一定要用type 2, 所以If I were you依啲幻想/假設性質就一定要用past tense.