回族食风中，伊斯兰教“清真”色彩极浓，严格遵循饮食（）。 A.二禁 B.三禁 C.四

下列变化属于物理变化的是

A．木材烧炭

B．玻璃破碎

C．燧木取火

D．铁矿石炼铁

对小企业进行信用风险分析时，应关注（）等风险点。

A.产品多样化

B.可能出现逃债现象

C.自有资金匮乏

D.很少开具发票

E.经不起原材料价格波动

计算题：某矿井在总回风中测得瓦斯浓度为0.3%，总风量为12000m³/min，矿井平均日产煤量9000t，求矿井的绝对瓦斯涌出量和相对瓦斯涌出量。

频率的一次调整

The cost C of manufacturing a certain product can be estimated by the formula C=0, 03rst², where r and 8 are the amounts, in pounds, of the two major ingredients and t is the production time in hours. If r is increased by 50 percent, s is increased by 20 percent，and t is decreased by 30 percent, by approximately what percent will the estimated cost of manufacturing the product change ？（）

A．40%increase

B．12%increase

C．4%increase

D．12%decrease

E．24%decrease