Three years has passed ever since _____.

Soon after the PRC was set up, a new law was passed which _______ people’s freedom of speech, religion and demonstration.

Experiments of this kind ___in both the U．S and Europe well before the Second World War

Only when the war was over ________ returnto their hometowns.

________ excited Geoff Marcy most was whether therewere planets in other solar system where life might exist.