---You didn’t lock the back door.
一You are wrong．I .
A．have locked it B．lock it myself C．did lock it D．do lock it
Companies in Zhongguancun all have their own characteristics, but they all share spirit of creativity and scientific skill that have made Zhongguancun success．
A．the; a B．不填; a C．the;不填 D．a；a
Who do you think will _______ since the president has resigned?
A．take over B．take up C．take in D．take off
--How was your weekend, Rose?
--Awful! This was the first time I ________ alone at home, bored to death.
A．had left B．had been left C．have been left D．have been leaving
Many citizens urged their government to take measures to _______ their carbon emission to reduce greenhouse effects.
A．cut off B．cut up C．cut out D．cut down
Obama made _______ history by being elected as ________ first black president of the US.
A．不填；the B．a; the C．a; a D．the; a
