Correct. The present continuous tense is used to talk about pre-planned future events.

Correct. ‘Hadn’t had’ is the past perfect tense form of the verb have. When we use ‘would have + past participle’ in the main clause, the verb in the if-clause should be in the past perfect tense.

Correct. After ‘would rather’, we use past tense with a present or future meaning.

Correct. The past perfect continuous tense is used when we describe a past event as continuing up to a particular time in the past.

We use the future perfect or future perfect continuous tense to say that something will have been done by a certain time in the future. Although both of these tenses have similar meanings, the future perfect continuous is used to emphasise the continuity of a future achievement.

For something scheduled in the furure we use simple present tense.

To suggest the completion of an activity in the unspecified or unknown past, we use the present perfect tense. In this case, the speaker doesn’t say when he did the shopping. Here the emphasis is merely on the idea of completion.

To suggest the completion of an activity in the unspecified or unknown past, we use the present perfect tense. The present perfect tense is not used with a past time of reference. In that case, we have to use the past simple.

It is a fact that developing nations need fossil fuels and we use simple present to talk about facts. The present continuous tense is used to talk about an action that is in progress at the moment of speaking.

Facts should be in the simple present tense.

Correct. We use the present simple tense to talk about facts.

Some verbs refer to states. Examples are: like, hate, believe, understand, etc. Verbs wich refer to state are always used in their simple forms.

When the verb in the main clause is in simple future tense, we use present tense in the subordinate clause to refer to the future.

‘Had had’ is the past perfect tense form of ‘have’. If the verb in the if-clause is in the past perfect tense, we have to use ‘would have + past participle’ in the main clause. This sentence can be written in three ways. (Type 1 conditional) If I have enough money, I will buy you a drink. (Type 2 conditional) If I had enough money, I would buy you a drink. (Type 3 conditional) If I had had enough money, I would have bought you a drink. 

Correct. ‘Had had’ is the past perfect form of the verb have. The past perfect tense is used when we are talking about the past and want to refer back to an earlier past time.

‘Had had’ is the past perfect form of the verb ‘have’. In type 3 conditional sentences, we use past perfect tense in the if-clause and ‘would have + past participle’ in the main clause.