"I go to the mosque yesterday for Friday prayers."
"went"
"My family always eats dinner in 8:00 PM."
"at"
"I want to be an doctor when I graduate from secondary school."
"a"
"I have many homeworks to do for my DSE classes tonight."
"homework" (or "a lot of homework")?
"I likes to drink hot chai in the morning before school."
"like" (Subject-verb agreement: "I" takes the base verb).
"She is living in Tsim Sha Tsui since 2015."
"has been living"
"My older brother is very good in speaking Urdu and English."
"at"
"We took a minibus to the Victoria Peak last weekend."
removing "the" (just "Victoria Peak")
"The informations provided by the teacher was very helpful."
"information"
"The star ferry is a cheap and scenic way to cross the harbour."
"Star Ferry"? (Proper nouns require capitalization).
"We did not played cricket in the park on Sunday."
"play"? (After "did not," the base form of the verb must be used).
"My grandfather moved at Hong Kong many years ago."
"to"
"He bought a new phone in Sham Shui Po, but a phone was broken."
"the" (The second time a noun is mentioned, it becomes specific).
"There are less students in the classroom today because of the flu."
"fewer" (Use "fewer" for things you can count, like students).
"Although it was a typhoon, but we still had to study at home."
removing "but" (or removing "Although")? (You cannot use both conjunctions in the same sentence).
"By the time the MTR arrived, I already finish my vocabulary list."
"had already finished"
"I am looking forward to see my cousins during the Eid holidays."
"seeing"(The phrase "look forward to" must be followed by a gerund/noun).
"My family absolutely loves eating the biryani."
removing "the" (just "biryani")? (No article is needed for general, uncountable food items).
"We bought three new furnitures for our flat in Kowloon."
"pieces of furniture" (or just "furniture")
"Every of the students in my English class works very hard."
"Every one" (or "Each")? ("Every" cannot be followed immediately by "of").
"If it will rain tomorrow, the school picnic in Sai Kung will be cancelled."
"rains" (In a first conditional sentence, the "if" clause uses the present tense).
"She was congratulated for winning the inter-school speech festival."
"on"
"My sister plays piano beautifully at the school assembly."
"the piano"? (Musical instruments require the definite article when talking about playing them).
"The staffs at the halal restaurant were very friendly to us."
"staff"? (Staff is a collective noun and rarely takes an 's').
"Neither my brother or my sister likes eating spicy food."
"nor" (The correlative conjunction pair is "neither/nor").