YJ19A卷烟机旋转式喇叭嘴可选用三套式或两套式喇叭嘴座。

_______not to be late for the meeting, we arrived forty minutes _______ the required time, but after _____seemed hours of waiting, we were informed the meeting had been canceled.

A．So as; ahead of; what

B．In order; ahead of; what

C．So as; in advance of; it

D．In order; ahead of; it

-What do you think of maths?

-My favourite. It's ________ for me to study of all the subjects in school.[ ]

A. more difficult

B. the most difficult

C. less difficult

D. the least difficult

【说明】
非对称数字用户线(ADSL)是接入Internet的一种宽带技术，图7-7为一台带网卡的PC机采用ADSL方式接入Internet的网络结构图。现在比较成熟的ADSL标准有两种：G.DMT和G.Lite。其中，G.DMT标准支持的最高上行、下行速率分别为1.5Mb/s、8Mb/s，G.Lite标准支持的最高上行、下行速率分别为 512Kb/s、1.5Mb/s。

【问题1】
请将图7-7中(1)、(2)空缺处的设备名称填写完整。

注水泵的并联提高了注水站的运行调度的（）和供水的可靠性.

A.连续性

B.均匀性

C.灵活牲

D.持续性

胚胎干细胞是从（）时期的胚胎中分离得到的。