学习并不是劳力劳动，而是脑力劳动。

Studying isn't manual labor, it's brain work.

脑力劳动的成果取决于你精力的多少。

Mental work is a result of your energy levels.

在土木工程中，桥梁设计大概是艰苦的脑力劳动了。

Bridge design is probably the hardest brain work in civil engineering.

经常脑力劳动的人或者夜以继日刻苦学习的学生朋友们，应当多喝菊花茶。

People who use their "brain" to work or students who study hard day and night.