煤气制气中一氧化碳含量较多，为了解决一氧化碳含量较高的煤气使用安全问题，对煤气进行加臭是国外已成熟的安全措施之一。
参考答案：对
—Did your mother do anything special on your birthday?
—Yes. She made me a cake in the ______ of a heart.
A．height
B．shape
C．style
D．number
