— Which share is meant for me?— You can take          half. They are exactly the same.

 —Did ________ of your parents come to attend the opening ceremony? — ________ of them came. 

The threats to the health of astronauts in space are very different from ______ on earth. 

    _ may have a chance to be successful if he tries his best.

(2013·高考安徽卷)This project requires close teamwork.________ will be achieved unless we work well together.