Invention can be ________ as it may suddenly begin just by noticing something usual.
—I’ve told Nancy many times about the meeting, but she still forget it! —I understand. Actually, anyone ______ be very forgetful at times.
— David, keep ______ in mind that you have to be home by 10 o'clock. — OK, Mom, I will.
The lift ______ and we were trapped inside it.
______ all my homework unfinished, I am not allowed to go online to play games.
A 3G mobile phone, ______to be most useful and fashionable, is popular with some teenagers.