1.If we go by train, it will be cheaper.
=> Should we go by train, it will be cheaper.
2. If Lan doesn't hurry, she will be late.
=> Unless Lan hurries, she will be late.
3. I don't have a map, so I cannot lend it to you.
=>If i had  a map, I could lend it to you.
4. If I were your mother, I would insist you study harder.
Were i your mother, I would insist you study harder.
5. If you had known my boss, you would have thought he was talented.
=> Had you known my boss, you would have thought he was talented.