单项选择题
But the changes go further than that. Take, for instance, the age at which people make commitments such as buying a house, getting married, having children, or starting a career. These are all fundamental commitments that are now occurring later in life. In 1962, 50% of Americans were married by age 21. By 2014, that milestone had shifted to age 29.
3. It can inferred that people tend to postpone marriage in the United States. ( )
A．对
B．错
But the changes go further than that. Take, for instance, the age at which people make commitments such as buying a house, getting married, having children, or starting a career. These are all fundamental commitments that are now occurring later in life. In 1962, 50% of Americans were married by age 21. By 2014, that milestone had shifted to age 29.
3. It can inferred that people tend to postpone marriage in the United States. ( )
A．对
B．错
时，给热系数α与加热面的 无关，此区称为 。