1. What do the following words have in common?

SIGHING
CANOPY
PASTURE
DEFINE
THIRSTY

2. What do the following words have in common - other than ending in ING?

ASPIRING
RAISING
RUING
THING

HINT:
1. Think alphabetically.

Answers:

1. Each word contains three consecutive letters of the alphabet in consecutive order. 

2. The final G can be dropped from each word, leaving a valid word:

ASPIRIN / RAISIN  / RUIN / THIN

Credit #1: GAMES Magazine - Jan. 1987
Joan Leary
HIJINKS (adapted)