放坡基坑施工中，分级放坡时，宜设置分级过渡平台，下级放坡坡度宜()上级放坡坡度。
A. 缓于
B. 陡于
C. 等于
D. A或B或C
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当本侧收发信机发信功率为10W而对侧收信功率为2W时，通道衰耗等于（）。注：lg2取0.3。
A. 8db
B. 7db
C. 5db
D. 2d
Which of the following statements is true when the database is in ARCHIVELOG mode and tablespaces are in hot backup mode？（）
Archive log generation is suspended until the tablespaces are taken out of hot backup mode.
B. Datafiles are not written to during hot backups.
Changes to the database are cached during the backup and not written to the datafiles to ensure that the datafiles are consistent when recovered.
D. The datafile headers are not updated during the backup.
E. The way data is written to the online redo logs is unchanged during the backup.
房屋建筑的安全责任人是指房屋建筑的（）
A. 开发建设单位
B. 所有人
C. 使用人
D. 管理人
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