(A):3个空位:
She has [discovered] [who] [sells] fruit cheaply.
She has [learnt] [who] [sells] fruit cheaply.
(B):或4个空位:
She has [discovered] [where] [to] [buy] fruit cheaply.
She has [learnt] [where] [to] [buy] fruit cheaply.
(A):3个空位:
She has [discovered] [who] [sells] fruit cheaply.
She has [learnt] [who] [sells] fruit cheaply.
(B):或4个空位:
She has [discovered] [where] [to] [buy] fruit cheaply.
She has [learnt] [where] [to] [buy] fruit cheaply.