His mind is always busy thinking scientific problems and seldom notice what is going on around him.

他的头脑总是忙着思考科学难题，以至他很少留意他周围的事。

youdao

His mind is always busy thinking scientific problems and seldom notice what is going on around him.

他的头脑总是忙着思考科学难题，以至他很少留意他周围的事。

youdao