Large pipes or down-comers are fitted between the steam drum and （） to ensure good natural circulation of water. ["fire-tubes","furnaces","water drums","water wall tube"]
根据国际半导体技术路线图组织的预测，未来集成电路有哪两个发展方向？
Records of tests and inspections of a cargo vessel’s fire extinguishing systems shall be kept on board（）. ["for 1 year","for 2 years","until the next Coast Guard inspection","until the vessel's Certificate of Inspection expire"]
中国现代礼仪是从什么时候开始形成的？
简述毛细线虫的生活史。
简述毛细线虫病的症状和病理变化。
