Creating world peace is a rather difficult goal, ____ calls for efforts of many generations.

31．Chicago lies _________ the two rail roads are connected

Edward, you play so wellBut I ________ you played the piano

anager of the factory wants to improve production a great deal, but he doesn’t spend much on technology.– I am afraid he won’t realize his dream. You know ________.

Don’t worry about your broken pen．You can use ．