1. He is on a business trip.
他现在出差了。
还能这样说：
He's on business now.
He is taking an official trip.
谚语：
Better the foot slip than the tongue trip.
宁可失足，不可失言。
2. He is off today.
他今天放假。
还能这样说：
He is on vacation.
He isn't working today.
应用解析：
be badly off 生活贫困，运气不佳；
be comfortably off 生活宽裕；
be better off 情况好些，生活比较宽裕；
be worse off 情况更差，更加贫困；
from the off 从头开始
3. He is not in now.
他现在不在。
还能这样说：
He is out now.
He is not here now.
4. He's out to meet with customers now.
他外出见客户了。
还能这样说：
He's out to see clients right now.
He goes to see the clients.
谚语：
Don't make a mountain out of a molehill.
不要小题大做。