锅炉上水期间，应控制汽包上下壁温差不超过（）。 ["20℃","80℃","40℃"]
抵押是合同当事人用自己一定的财产来向对方保证自己履行合同义务的担保形式。
What are two circumstances for which it may be advisable to use the silent uninstallation method instead of an interactive method？（） [" The Administrator is unable to successfully export DISPLAY to a remote server."," IBM Tivoli Workload Scheduler is installed on a server for which there is no console access."," DNS is not working properly and the server cannot be accessed remotely to run the uninstallation script."," TCP on the server on which IBM Tivoli Workload Scheduler is installed is configured for half-duplex rather than full-duplex."," The remote IBM Tivoli Workload Scheduler server is multi-homed， thus the return connection to IBM Tivoli Workload Scheduler cannot be established thereby requiring the use of the silent uninstaller."]
What is the result？（） ["The code will deadlock.","The code may run with no output.","An exception is thrown at runtime.","The code may run with output "0 6".","The code may run with output "2 0 6 4".","The code may run with output "0 2 4 6"."]
儿童期最早出现的游戏形式是（） ["感觉运动游戏","象征性游戏","结构游戏","规则游戏"]
离心泵卡圈（口环）径向间隙的大小取决于输送的介质和（）的大小。
