How to use COULD as an auxiliary in English?
We use this auxiliary ‘could’ in many cases. 1. In as the past equivalent of ‘can’ in complex sentence. 2. In past tense for past actions. 3. The term ‘could’ is more polite than ‘may’ which is used for making polite requests in simple present tense and future tense. 4. In simple present tense for purpose of ability or possibility. 5. In future in the past tense this ‘could’ is used. Let us come to know about some rules of tenses where this ‘could’ be used. 1. For simple present tense in the present form of the verb the auxiliary is ‘could’. 2. For present continuous tense in the present-in-ing form of the verb the auxiliary is ‘could be’. 3. For future tense in the present form of the verb the auxiliary is ‘could’. 4. For future continous tense in the present-in-ing form of the verb the auxiliary is ‘could be’. 5. For simple past tense in the present form of the verb the auxiliary is ‘could’. 6. For future in the past tense in the past participle form