____ is to be done is ______ to carryit out smoothly since the decision has been made．

The two girls are so alike thatstrangers find ____ difficult to tell one from the other

This machine It hasn’t workedfor years

Praise is like sunlight to the human spirit； without _____we cannot flowerand grow

My grandfather used to build railways for the Japanese army(军队) when he was young. He was ______ to work hard from morning till night.