PLEASE COME IN1-Why I couldn't get you on the phone this morning.-we __tennis in the yard when you phoned me.A must be playing B must have been playing2-do you still remember when we went to the Great Wall?-I can't remember it well,but __it have been

PLEASE COME IN1-Why I couldn't get you on the phone this morning.-we __tennis in the yard when you phoned me.A must be playing B must have been playing2-do you still remember when we went to the Great Wall?-I can't remember it well,but __it have been
PLEASE COME IN
1-Why I couldn't get you on the phone this morning.
-we __tennis in the yard when you phoned me.
A must be playing B must have been playing
2-do you still remember when we went to the Great Wall?
-I can't remember it well,but __it have been sometime last May
a should b could
嘎,两题都应该是B，但为什么呀
1ses340403说------B,(表示过去正在发生的事) A不能表示过去正在发生的事吗？

PLEASE COME IN1-Why I couldn't get you on the phone this morning.-we __tennis in the yard when you phoned me.A must be playing B must have been playing2-do you still remember when we went to the Great Wall?-I can't remember it well,but __it have been
1-Why !I couldn't get you on the phone this morning.
-we __tennis in the yard when you phoned me.
A must be playing B must have been playing
only must have been doing indicates what was happening in the past..
A is not correct in that it indicates only what is happening ,not what was happening
2-do you still remember when we went to the Great Wall?
-I can't remember it well,but __it have been sometime last May
a should b could
Here,the person who responded does not have any certainty with respect to the statement.Thus could is used,whereas should imples a certain degree of certainty

1.A 正在玩么？？？？用进行时
2.B could表示逻辑上的猜测

1-Why I couldn't get you on the phone this morning.
-we __tennis in the yard when you phoned me.
A must be playing B must have been playing
------B,...

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1-Why I couldn't get you on the phone this morning.
-we __tennis in the yard when you phoned me.
A must be playing B must have been playing
------B,(表示过去正在发生的事)
2-do you still remember when we went to the Great Wall?
-I can't remember it well,but __it have been sometime last May
a should b could
-------B，（虚拟语气的倒装结构）
补充：
1ses340403说------B,(表示过去正在发生的事) A不能表示过去正在发生的事吗
---这种句型have 才表示过去

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第二题选A

A must be 表示对过去的肯定推测
A should