When a customer withdraws money from the bank, it is required to leave his signature. But how can we be sure it is_______?

Over one thousand passengers remained_____ on trains for hours without air conditioning because of power failure on the railway,  

The situation is _________—we have no food, very little water and no medical supplies. 

-Life itself tells us it is necessary to learn to be     .One can hardly survive without help from other people in the world.

—Do you believe his words?  —No, what he said was________.