<p>The library is older than it but still just as beautiful as the courthouse. </p>
<p>A. older than it but still just as beautiful s the courthouse
B. older and it is just as beautiful as the courthouse
C. old than the courthouse; it is just as beautiful as it
D. older than the courthouse but just as beautiful
E. just as beautiful as the courthouse and it is older than it</p>
<p>the right is D, but i don't know the reason.</p>
<p>Besides, i find difficulty in understanding the "than" and "as...as"</p>
<p>is it necessary to follow this formula that the verb before than or as must be repeated after than or as?</p>