____________ to think critically is an important skill today's children will need for the future.
Learn
Learned
Learning
Having learned
________ anyone come to my office, please tell them I'm not available before four o’clock.
Had he not come an hour earlier, he___the secret that his mother was always there.
---- What do you think of a house supplied by Lovell ? ---- _______ you buy a home from Lovell, the company promises to buy it back at the same price after three years.
Had the government limited the sales of cars much earlier, traffic jam and pollution _______so serious now.
____today, he would get there by Friday.