In Russian both variants, with can and could, are rendered in the same way: Неужели это правда?, Неужели она лжет? and so on

Possibility due to circumstances,

e.g. You can see the forest through the other window.

In past-time contexts the form could is used. It is followed by the simple infinitive in this case.

e.g. You could see the forest through the other window before the new block of houses was erected.

The form could in combination with the simple infinitive may also express unreality with reference to the present or future.

e.g. You could see the house from here if it were not so dark.
In combination with the perfect infinitive, could indicates that

the action was not carried out in the past.

e.g. You could have seen the house from there if it had not been so dark.

Permission,

e.g. You can take my umbrella.

In this meaning can is combined with the simple infinitive.

The form could with reference to the present is found only in interrogative sentences in which it expresses a more polite request.

e.g. Could I use your car?

Uncertainty, doubt,

e.g. Can it be true?

Depending on the time reference, can in this meaning is used in combination with different forms of the infinitive.

Thus, if reference is made to the present, the simple infinitive is found with stative verbs.

e.g. Can he really be ill? Can it be so late?

With dynamic verbs, the continuous infinitive is used. e.g. Can she be telling lies?

Can he be making the investigation all alone?
Can in combination with the perfect infinitive refers the ac-

tion to the past.
e.g. Can he have said it?

Can she have told a lie?

The combination of can with the perfect infinitive may also indicate an action begun in the past and continued into the mo- ment of speaking. This is usually found with stative verbs.

e.g. Can she really have been at home all this time?
However, if can is followed by a dynamic verb the Perfect

Continuous infinitive is used.
e.g. Can she have been waiting for us so long?

Could with reference to the present is also used in this way, implying more uncertainty.

e.g. Could it be true?
Could she be telling lies?
Could he have said it?
Could she have been waiting for us so long?

In Russian both variants, with can and could, are rendered in the same way: Неужели это правда?, Неужели она лжет? and so on.

5) improbability,
e.g. It can't be true. (Это не может быть правдой. Вряд ли это так.)

Could is also used in this way making the statement less cate- gorical.

e.g. It couldn't be true.
She couldn't be telling lies.
He couldn't have said it.
She couldn't have been at home all this time. She couldn't have been waiting for us so long.

§ 78.in special questions where they are used for emotional co- louring (for instance, to express puzzlement, impatience, etc.).

e.g. What can (could) he mean?
What can (could) he be doing? What can (could) he have done? Where can (could) he have gone to?