▲关于第1句：

even属副词（当然还是形容词和动词），但不用作连词。许多中国学生受汉语影响，以至于出现这样的句子：Even you try again, you may not succeed. （这个句子是错误的，需在Even后加if。）

所以，They’ll stand by you even you don’t succeed. 也是错的。

▲even if 和even though的区别：

两者均可引导让步状语从句，但稍有差别：

1. even if 引导的从句是往往是假设性的，相当于汉语的“即使”，“纵然”，“就算”。如： Even if I fail this time, I would try again. 即使我这次失败了，我还要再试试。

We should practice economy even if we are rich. 即使我们富裕了也仍应该厉行节约。

We'll go even if it rains. 即使下雨我们也要去。

Even if you saw him pick up the money, you can't be sure he stole it. 就算你看见是他拾起的钱，你也不能肯定钱就是他偷的。

Even if one graduated from college, he should still continue to learn. 即使大学毕业了他也要继续学习。

Even if he said so, you need not believe him. 即使他这么说，你大可不必相信他。

Even if it will take me six weeks, I am determined to finish the job. 即使这工作要花掉我六个星期的时间，我仍决心要把它完成。

2. even though 引导的从句内容往往是真实的，主要用于引出不利用于主句情况的信息，相当于汉语的“尽管”“虽然”。如：

He never apologizes, even though he knows that he is in the wrong. 他从不道歉，即使他自知错了。

I took the liberty of reading the letter, even though it was addressed to you. 尽管这封信是写给你的，但是我冒昧地看过了。

Even though I hadn't seen my classmate for many years, I recognized him immediately. 即使多年没有看见我的同学，我也马上认出了他。

He will come on time even though it rains. 即使下雨，他还是会准时来的。

Even though you do not like it, you must do it. 即使你不喜欢这工作，你也得做。

3. 不过，在实际语言中，even if与even though有时也可不加区别地混用。如：

Even if (Even though) she laughs at him, he likes her. 尽管她嘲笑他，他还是很喜欢她。 

We thoroughly understand each other, even if (even though) we don’t always agree. 我们彼此非常了解，虽然有时候也有一些分歧。