Grammar:

Tense	We use:	Time expressions	Example
Present simple:	Өдөр тутмын болон байнга давтагддаг үйлдэлд	-          every hours/week/month/summer -          usually, always, often, sometimes -          every morning/evening/nigh -          at  night	He starts his work at 9o’clock every morning. I play football in my free time.
Present continuous:	Яг одоо, энэ мөчид болж байгаа үйл явдлыг дүрслэнэ. Эргэн тойронд болж байгаа үйл явдлыг дүрслэнэ. Ойрын ирээдүйд хийхээр төлөвлөсөн үйлд	-          Now, nowadays -          At the moment -          These days -          At present -          Tonight	I am reading a magazine now. She is studying for a final exam. They are flying to Tokyo next week
Past simple:	Тодорой хугацаанд болоод дууссан үйлд Өмнө нь давтагддаг байсан боловч дахиж хийгдэхгүй үйлдэлд	-          Yesterday -          Last night/week/month… -          A year/two week ago… -          In 1991…	We started work at 8:30 yesterday He usually played football in his free time (тэр ахиж хөлбөмбөг тоглохгүй)
Past continuous:	Хэзээ эхэлсэн, хэзээ дууссан нь тодорхойгүй өнгөрсөнд болсон үйл Урт үйл болж байхад богино үйлдэл тасалдуулахад Өнгөрсөнд хоёр эсвэл олон үйл ижил цагт зэрэг явагдвал Үйл явдлын арын дэвсгэр болж өгвөл	-          When/while/as + PaCo(longer action) -          When + PaSimple (Shorter action)	I was reading a magazine at 5o’clock yesterday She was studying (longer actio) when the phone rang (Short action) Tina was doing the washing-up while the children were playing in the garden The sun was shining brightly as Tom was driving his brand new car through the city centre.