According to the Oxford Dictionary (2018), verb is a word th...

The subjunctive mood is used to express a wish or possibility. This mood has a limited role in English compared to other languages such as French or Italian, but it's important to use it properly in formal writing.

The subjunctive form of a verb (apart from to be) is made from the 3^rd person present singular, without the -s (or -es) ending. With these verbs, the same forms are used whether or not the context is the present or the past.

The subjunctive is typically found in rather formal English constructions with that and with verbs such as suggest, demand, insist, ask, recommend, etc.:

It was suggested that he wait till the next morning.

They demanded that the prime minister explain who authorized the action

The tense of a verb tells you when a person did something or when something existed or happened. In English, there are three main tenses: the present, the past, and the future.

The past tense (e.g. I was, he talked, we had, they worked) is also called the past simple or simple past. As its description implies, it‘s used to talk about things or situations which happened in the past, that is, before the present time of speaking. Its main uses are as follows:

1^st) to refer to an event or situation which happened once and is now finished;

2^nd) to describe a situation that lasted for a longer time in the past but is now finished; 3^rd) to talk about an event that happened regularly or repeatedly but is now over.

There are two further types of tense: the continuous and the perfect. These tenses are sometimes referred to as aspects rather than tenses. The term aspect is used in grammar to talk about the form of a verb that shows, for example, whether the action happens once or repeatedly, is completed or still continuing.

The continuous tenses (also called progressive tenses) are used to talk about actions that continue for a period of time. They are formed with the relevant tense of the auxiliary verb to be and the present participle of the main verb. There are three main continuous tenses: the present continuous (I am reading), the past continuous (I was reading), the future continuous (I will be reading).

Perfect tenses are typically used to talk about actions that are completed by the present or a particular point in the past or future. They are formed with the relevant tense of the auxiliary verb to have and the past participle of the main verb. There are three main perfect tenses: the present perfect (I have read), the past perfect (I had read), the future perfect (I will have read).