1. as if/ as though…..(表示与事实相反，用虚拟;若表示即将成为事实或有可能成为事实，则用陈述语气)
1). He was in great trouble, but he acted as if nothing had happened.
2). Although they just met for the first time, they talked as if they had been friends for many years
3). The clouds are gathering. It looks as if it is going to rain.
2. n. /adj. / adv. / v. + as / though +主语+谓语，…… 尽管……,…….引导让步状语从句
1).Child as he is, I already know what career I want to follow.
2). Try as he might, he couldn’t solve the problem.
3). Much as I respect him, I can’t agree with his idea.
3. whether….or…. 无论是….还是….
1). Whether the weather is good or bad, they will set off as they planned.
2). Any person, whether young or old, has his own worth.
4. 疑问词+ever = no matter +疑问词, 引导让步状语从句或名词性从句
1). Whichever(=No matter which) you like, you can take it away .( 让步状语从句)
You can take away whichever(=any one that) you like ( 名词性从句)
2). Whenever you comes, you will be welcome. ( 让步状语从句)
3). Whatever happens, I will support you. ( 让步状语从句)
4). Whoever breaks the law, he will certainly be punished. ( 让步状语从句)
à Whoever breaks the law will certainly be punished. ( 名词性从句)
5). However great the difficulty is, we can overcome it. ( 让步状语从句)
5. if/ as long as/so long as/ providing that/ provided that/ supposing that/ on condition that 假如…..
1). I will lend you money on condition that you can return it within 3 months.