Expressing "even if…" with 即使...也 (jíshǐ... yě)

即使...也 (jíshǐ... yě) means "even if...still...". In this construction, the first clause (after 即使) is a supposition, which is then struck down as impossible by the second clause (after 也) of the statement. The structure is 即使 + hypothetical statement + 也 + action. For example, 
即使明天下雨，我们也要去爬山 。 Even if it's raining tomorrow, we're still going to go out hiking.

Note that the clause used after 即使 must be hypothetical, otherwise 虽然 should be used. For example, 
虽然现在是交通高峰期，我也要去。Although it is the rush hour, I still want to go. 
即使现在是交通高峰期，我也要去。(wrong!)

Please say the following sentences in Chinese:

1. Even if it should rain tomorrow, we will continue our work.
2. Even if we achieve great success in our work, we should not be conceited.
3. Even if  he failed , he would try again .
4. Even if he were my own son, I would still say he is wrong.