External hard disks can be purchased alone and then attached to the microcomputer with cables; they are used for backing up large amounts of data or for additional storage capacity. 內部硬盤(pán)永久性地安置在微機內，只有需維修或更換時(shí)才取出。外部硬盤(pán)可以獨立購買(mǎi)，通過(guò)電纜線(xiàn)與微機相連。
The body cannot tolerate such large amounts of radiation. 身體經(jīng)不住那么大劑量的放射線(xiàn)。
One of the main disadvantages of this system is that it uses very large amounts of fuel. 該系統的主要弱點(diǎn)之一是消耗大量燃料。
