不仅。。。而且 - means not only but also. It is a sentence structure expected of GCSE students and is considered a complex sentence structure. 不仅 and 不但 are interchangeable. The structure goes S +不仅 + V+O, 而且/还+ V + O. In oral answers the student is expected to use at least one complex structure to get into the highest band. This is an example of one.