Many clothing manufacturers now substituteartificial silk _____ natural silk to cut down costs of production

Studies show that people are more tosuffer from back problems if they always sit before computer screens for longhours.

How soon will you send the book to me? —-It will be two days _______ you receive my book

Wow! Your school is so beautiful!—Thank you! It _____ last year.

If you can’t do it ,you can ask me for help .