甲、乙双方于2006年4月1日签订一份建筑材料购买合同，合同约定一旦乙收回前欠应收账款，立即给甲的银行账户汇款购买其材料，并约定如果一个月内不能履行，则合同失效。4月10日，乙的银行账户收到15万元前欠货款，乙于当日即向甲汇款，履行了合同。根据《中华人民共和国合同法》的规定，这份购买合同的生效日期是()。
A. 2006年4月1日
B. 2006年5月1日
C. 2006年4月10日
D. 2006年5月10日
查看答案
Mr. Bush's attitude toward the public's remarks is ______.
A. consent
B. hesitation
C. denial
D. approval
It can be inferred from the last paragraph that ______.
A. new methods to prevent terrorism on aero-planes are not a panacea
B. new equipment will be mass-produced commercially over the next 12 months
C. new methods are readily monitored by security staffs at the airport
D. new equipment can only detect minute traces of explosive
According to the text, the current research concentrates on ______.
A. the charger
B. duration of the device
C. the internal batttery
D. human transplants
In contrast to Dr. Connolly's study, the previous ones failed to ______.
A. make a comparison between the experience of scientists in others kinds of laboratory and that of those in universities
B. make themselves more eligible for promotion
C. make a difference for a woman to settle into a professorial chair
D. make the supposedly egalitarian world of academia deliver more equality
微信支付 
支付宝支付