1.He can't join our trip Hanoi
->We wish he could join our trip Hanoi
2.The weather was bad,but we went to school on time.
->Although the weather was bad , we went to school on time.
3."Why don't you ask your teacher for advice?" my brother said to me. (suggest)
->My brother suggested that I (should ) ask my teacher for advice
4.His sister isn't old enough to get married.(too)
->His sister is too young to get married