1) Attentive 2) Careful 3) Diligent 4) Helpful 5) Scrupulous 6) Sedulous 7) Untiring 1) Constant 2) Diligent 3) Hard-working 4) Industrious 5) Persevering 6) Sedulous 7) Working diligently at a task 
• (a.) Performed with constant diligence or attention; unremitting; persistent; as, assiduous labor. • (a.) Constant in application or attention; devoted; attentive; unremitting.
As·sid'u·ous adjective [ Latin assiduus , from assid...re to sit near or close; ad + sedēre to sit. See Sit .] 1. Constant in application or attention; devoted; attentive; unremitting. « She grows more assiduous in her attendance. ...
diligent hard-working sedulous 
[adj] - marked by care and persistent effort
assiduous 1. Constant in application or attention; unremitting diligent: 'She was an assiduous worker who strove for perfection.' 2. Unceasing; persistent: 'He was always doing assiduous research for his project.' 3. Constant in application or effort; working diligently at a task; persevering; industrious; attentive: 'Bob was an assiduous student...
sedulous adjective marked by care and persistent effort; `her assiduous attempts to learn French`; `assiduous research`; `sedulous pursuit of legal and moral principles`
constant; unremitting: assiduous reading. · constant in application or effort; working diligently at a task; persevering; industrious; attentive: an assiduous student.
marked by care and persistent effort[Intelligent words] marked by care and persistent effort