Sea water ______ many minerals, salt ______.

We’ll go out for a walk after supper. Will you        us?

—How do you__________ we go to Beijing for our holidays? —I think we’d better fly there. It’s much more comfortable.

--- Can I help you, sir?---I’m afraid you can’t. I have my students’ papers________.

Science and technology is changing fast nowadays. I bought this MP3 player at the beginning of this year but now it's out of ________.