Working hard ________ the key _________ success of everything.
The old scientist has made a great contribution the moon.
—What is the table made _______?—Wood.
Many countries have a lot of rockets into space.
—How can I learn English well?—You will learn it well ________ you practice speaking it often.
—Are you ready to leave, Helen?—_________—I was just asking if you’re ready to leave.