对空气系统进行气密性试验时，其试验压力不得小于其工作压力。
参考答案：对
孕酮刺激导致卵内cAMP水平下降的主要原因（）
A、Ri受刺激
B、Rm受抑制
C、磷酸二酯酶活性增加
D、其他
A semiannual-pay bond is callable in five years at $1080. The bond has an 8% coupon and 15 years to maturity. If an investor pays $ 895 for the bond today, what are the yield to call (YTC) and the yield to maturity (YTM), respectively YTC YTM（）①A. 10.77% 9.31% ②B. 12.07% 9.31% ③C. 10.77% 10.21%
A. ①
B. ②
C. ③
