The only grammatical error I see is "is happened". Instead, say "happens" or "has happened". Everything else is correct. I am not enthusiastic about the first two sentences though. The use of "consistent" bothers me because as an adjective, "consistent" modifies "I" (the subject of the sentence). However, your intention is for "consistent" to modify what you have been doing. That purpose is better accomplished by an adverb: "I have been consistently studying English." I feel that is much better because "consistently" now modifies the verb "have been", and that is what you want. To further convince you that the adjective form is a poor choice, rewrite your sentence in this identical way: "Consistent, I have been studying English" in which "consistent" clearly modifies "I". It is not wrong but it sounds odd. I don't think it sounds natural.

Instead of consistent, try diligent. Feels like a better fit as a descriptor for that context. Hope this helps!

Here’s feedback on each sentence: 1. Lately I have been consistent in studying English.
✔️ Correct and natural. 2. I was consistent in studying English last month.
✔️ Correct and natural. 3. They blow their nose when they are sick.
✔️ Correct and natural. 4. They laugh when something funny is happened.
❌ Not quite right.
Replace with:
They laugh when something funny happens.
("Is happened" is incorrect because "happens" is the right form for present simple here.)

Hi Angela. Here what I reccomend: 1. I've been consistent in studying English lately; 2. Last month I was more consistent in studying English 3. When they're sick, they blow their nose (or when it happens they have a cold, they blow their nose). But it's ok even in the way you said. 4. They laugh when something funny happens Have a nice day 🩷