数字化变电站是基于（）来实现变电站信息采集、传输、处理、输出过程全部数字化。A、光电

结肠癌最早出现的临床症状是（）。

A.腹部肿块

B.全身症状如贫血、消瘦、低热等

C.肠梗阻症状

D.排便习惯和粪便性状的改变

E.阵发性绞痛

防止SAH后再出血的方法是（）。

A.卧床休息4~6周

B.保持大便通畅

C.不再从事剧烈运动或重劳动

D.保持血压稳定

E.对先天性动脉瘤或脑血管畸形者行手术治疗

把两米的木头锯2次，并且使每段长度相同，则每段是全长的______，每段长______米．

根据对话内容，补全对话，使其意思完整。每空只填一个词，将答案写在后面的横线上。

A: Hi!

B: Hi,Mary!

A: Did you 1._______ a good time last Sunday?

B.Yes, we did. We 2._______ out for a picnic.

A: Great! Where did you have it?

B: At the foot of the Great Wall.

A: With 3._______ did you go?

B: I went with Peter, Jim, Lucy, Lily and Jenny.

A: What time did you start?

B: At 8:30 in the morning.

A: 4.______ did you go there?

B: We went there by bike.

A: What did you have 5._______ lunch?

B: We had Beijing duck, chicken, eggs, bread and fruits.

保护地栽培的特点有哪些？