胚盘是鸟卵发育的起始部位．

从方框内选择最佳选项完成对话。

a. Would you like some orange juice?

b. Thanks for inviting me. 

c. It tastes nice and a little sour. 

d. Let me have a try. 

e. I'm very happy you like the food.

A: The fish soup is ready.

B: ____ Oh! It's a little salty but delicious.

A: This is Italian pizza.

B: ____ What's in it?

A: I put some tomatoes in it.

B: Good!

A: ____ 

B: Yes, please. Oh, it's very fresh and cool.

A: ____ 

B: ____ 

A: You're welcome.

①青藏高原   ②柴达木盆地   ③塔里木盆地   ④东南丘陵   ⑤内蒙古高原

如图所示的虚线区域内，充满垂直于纸面向里的匀强磁场和竖直向下的匀强电场。一带电粒子a（不计重力）以一定的初速度由左边界的O点射入磁场、电场区域，恰好沿直线由区域右边界的O′点（图中未标出）穿出。若撤去该区域内的磁场而保留电场不变，另一个同样的粒子b（不计重力）仍以相同初速度由O点射入，从区域右边界穿出，则粒子b（    ）