If I were you, I would take the risk. 假如我是你，我會冒險。
He seems to have been to Paris. 他似乎去過巴黎。

表質疑用can, like 他(can)是好人嗎
表假設用would, like 你(would)來吃飯嗎
表猜測用should, like 他走路變慢(should)是生病了

1. If I were you, I would study hard. 我要是我，我就會努力學習。 2. If I had studied hard, I would have passed CET-6 last semester. 如果我上個學期努力學習了，我就通過六級考試了。 3. If I were to pass CET-6, I would treat you to dinner at KFC. 如果我要是過了六級考試，就請你去吃肯德基。 4. Had it not been for the PLA, we wouldn't have been able to beat the flood. 要不是人民解放軍，我們是無法戰(zhàn)勝洪水的。 5. If I'd left sooner that day, I'd have been there on time. 那天要是我早點動身，我就準時到了。