1.Solar collector systems using water typically include a ______ mechanism to avoid freezing damage.
1.使用水作为介质的太阳能集热系统通常包含一种 ______ 机制，以防止冻结损坏。
2.The least allowable clearance between a rafter and an air duct is:
2.椽条与风管之间允许的最小净距为：
3.Heat tracing operation may be continuous or ______.
3.伴热操作可以是连续的，也可以是 ______ 的。
4.Flexible ducts must be supported at intervals no greater than:
4.柔性风管的支撑间距不得超过：
5.Nonmetallic return air ducts are allowed only if they:
5.非金属回风管仅在满足以下条件时才被允许使用：
6.Hot water heating systems are divided into low, medium, and ______ temperature ranges.
6.热水供暖系统按温度范围可分为低温、中温和 ______ 温度范围。
7.When a building uses a powered exhaust fan, the make-up air vent must be:
7.当建筑物使用动力排风扇时，补风口的大小必须：
8.Radiator and terminal unit manufacturers supply information regarding ______ losses within their equipment.
8.散热器和末端装置制造商通常会提供关于其设备内部 ______ 损失的信息。
9.The duct sizing method most often used by designers is:
9.设计师最常使用的风管定径方法是：
10.In a forced-air heating system, registers should be placed:
10.在强制送风供暖系统中，送风口（Registers）应设置在：
