兴奋时产生舒张支气管平滑肌效应的主要受体是（） ["α受体","α1受体","β1受体","β2受体","M受体"]
按GB5071-1996《液压电梯》规定，液压油缸上部必须设置（）。 ["蓄能器","安全阀","排气装置"]
碳酸锂重度中毒时的治疗措施，不正确的是（） ["减少碳酸锂剂量","停用碳酸锂","补液","利尿","人工透析"]
Why are the 1300 nm and 1550 nm regions of the fiber spectrum primarily used for optical communications？（） [" They are both regions of lowest loss."," They are both regions of low reflections."," They are both regions of low index of refraction."," They are both regions of low chromatic dispersion."," They are both regions of low Polarization Mode Dispersion （PMD）."]
清净分散剂
什么是软件？什么是软件工程？
