assiduous

"The student earned a good grade on the test by studying hard. "

"The preparation for the history test took her several hours. "

"Attendance at the meeting is required."

"The boat was hauled out of the water using the nearby hard. "

"He is a student of life."

"Scientists are very diligent in their work."

"I was very industrious in my effort to learn unicycle riding."

"The sergeant major is a regular in the British Army. "

"The construction crew's working on the new school building is going smoothly. "

"The exam of the child's handwriting revealed several areas needing improvement. "

"My work schedule is very demanding this week. "

"The player with the highest score is the winner."