You may find the examples dated, but the principles still hold true. =Although you may find the examples dated, the principles still hold true.
尽管书中的例子有些古老，但是其中原则在今天仍然非常适用。 总之注意一点：although和but不能连用。
可以。一般情况下在汉语中的许多词语，如“因为……所以”，“虽然……但是”，在英语中是不可以放在一起用的，但是中间如果有另一个分句，还是可以的。
although
she
is
very
tired
from
work,
she
has
a
backache,but
she
goes
on
working
during
the
night.
