1. What do the following words have in common?

BILL
TEST
CURB
DRAFT

2. What do the following words have in common?

FLOUR
TERN
THIRSTY

Answers:

1. Each word can be a synonym for CHECK. 

2. Dropping one letter from each word leaves a number:
    FLOUR - FOUR
    TERN - TEN
    THIRSTY - THIRTY 

Credits:
1: Brock Wilson
2: Will Shortz