I was really tired. However, I couldn't fall asleep.
correct
incorrect
She is my sister, but I don't get on with her.
incorrect
correct
He shouted loudly; however, nobody heard him.
incorrect
correct
I tried to lift the box. But, it was too heavy for me.
correct
incorrect
I help him, however he rarely helps me.
incorrect
correct
I exercise every day however I can’t seem to lose any weight.
incorrect
correct
They are close friends but totally different.
incorrect
correct
She didn't go to the match but she bought a ticket.
incorrect
correct
The street was crowded; however, nobody helped the injured dog.
incorrect
correct
She continued the journey but she was exhausted.
correct
incorrect
I watched the movie twice, I can't remember the ending.
incorrect
correct
She is five, but she is famous in many countries.
incorrect
correct
He was great at singing. But wasn't very confident.
incorrect
correct
She came to work, but was sick.
correct
incorrect
The book was good, but very long.
incorrect
correct