Now we are in basic D key,

Let's listen to the D scale first.

The first key roll call in the key of D is: do, la, so, mi, re, do,

The corresponding sound-name relationship is: D, B, A, F sharp, E, D.

When we want to switch to the key of G,

We need to raise the mi of D key by half a step on the basis of D key,

Let's listen to the G scale first.

The top key roll call in the key of G is: so, mi, re, do, la, so,

The corresponding sound-name relationship is: D, B, A, G, E, D.

When we want to tune the key of C,

We need to raise the mi and la of the D key by half a step on the basis of the D key.

We have raised mi just now, now raise la by a half step.

Let's listen to the scale of C,

The top key roll call in the key of C is: re, do, la, so, mi, re,

The corresponding sound-name relationship is: D, C, A, G, E, D.

When we want to tune the key of F,

On the basis of the key of D, the re, mi, and la of the key of D need to be raised by half a tone at the same time.

We have just raised mi and la,

Now raise re by a half step.

Let's listen to the F scale,

The first key roll call in the key of F is: la, so, mi, re, do, la,

The corresponding sound-name relationship is: D, C, A, G, F, D.

When we want to tune A,

We need to lower the do in the key of D by half a step on the basis of the key of D.

Now let's go back to the key of D,

Let's listen to the scale in the key of D,

We lower all the dos by half a step on this basis.

Let's listen to the A scale now,

The top key roll call in the key of A is: mi, re, do, la, so, mi,

Its corresponding sound-name relationship is: C sharp, B, A, F sharp, E, C sharp.

This is the tuning of the guzheng.