英语翻译in fig .1-7c all voltages are marked in the -to+sense in

英语翻译
in fig .1-7c all voltages are marked in the -to+sense
in going clockwise around the loop.the voltmeters are
connected as shown in fig.1-7d to measure voltages u'1,u'2
and u'3.nothing that the voltmeter readings are the same
as the variable values,we find that fig.1-7 fundamental
property of voltages around a loop Thus the sum of voltages
taken in the -to+sense around the loop adds up to zero.having
eq.(1-3a),we could have obtained eq.(1-3b)by recognizing that
in fig.1-7e u1 and u2 are designated in the + to
-sense,whereas u'3is designated in the -to+sense in going
clockwise around the loop.as show in fig.1-7f,the voltmeers
are connected so that they measure the vaeible values(not
their negatives).the result is.
which indicates that,around the loop,the sum of voltages
taken in the +to-sense equals the voltage taken in the -to
+sense,or the sum of voltages in one sense minus those in
the other sense is zero.by recognizing that u'3=-u3,we see
that eq.(1-3c) reduces to eq .(1-3a).alternatively,by using
u1=-u'1and u2=-u'2,eq.(1-3c) can be made the same as eq.(1-3).