Proper timing of fiscal policy is important if the government is to:（）

A. generating revenues from taxes and sales equal to its expenditures.

B. stimulate economic activity during a recession and restrain the economy during an inflationary boom.

C. increasing the supply of loanable funds needed to place downward pressure on the real rate of interest.

2010年世界环境日中国的主题是：低碳减排·绿色生活。下列做法符合这一主题的是[ ]

①小明做到草稿纸两面用，注意节约用水用电

②河南省决定公共机关停开一天公务车，同时要求公务人员的私车也停开一天

③许多宾馆倡议自带洗漱用品及牙杯，房间内将不提供一次性牙膏牙刷及牙杯

④河北省安平县为完成节能减排目标，限停居民生活用电

A．①②③

B．①③④

C．②③④

D．①②④