您要查找的是不是：
- This layer of rock contains a lot of flint. 这一岩层中有大量燧石。
- The inner layer of the wall of a spore. 孢子内壁孢子壁的内层
- There is a fine layer of dust on the desk. 桌子上有一层薄薄的尘土。
- Attendance at the meeting is mandatory. 出席会议是必要的
- The middle, usually fleshy layer of a fruit wall. 中果皮果皮中间通常含肉较多的那一层
- The bottom layer is a mixture of sand and clay. 最下面的一层是沙和泥的混合物。
- A reply to this letter is mandatory. 这封信非答覆不可。
- A fine layer of dust covers everything. 所有的东西都盖了一层薄薄的灰尘。
- mandatory layer 标准层
- Yet some form of attenuation is mandatory. 然而有些衰减形式是必须采用的。
- A layer, as of doubled-over cloth or of paperboard. 一层一层，如折叠过的布料或纸板的
- A surface, layer, or mass of frozen water. 冰面冻结的水的面、层或块
- A thin layer of bone, membrane, or other tissue. 骨骼、粘膜或其它组织的薄层
- Counseling is available, but not mandatory. 他们可以接受心理咨询，但没有人强制他们这样做。
- Assiduous respiratory care is mandatory. 我们强调精心的呼吸护理。
- The offence carries a mandatory life sentence. 这种罪行依照法律要判无期徒刑。
- Attendance is mandatory at all meetings. 所有会议皆不得缺席.
- A thin, flat layer or scale, as that of a fish. 外表组织薄而平的一层或鳞状物，如鱼鳞
- It is not mandatory to form OCs, however. 不过,当局并无强制规定成立法团。
- It is not mandatory to set a filter for a trace. 并不一定要为跟踪设置筛选器。
