The system has been designed to give students quick and easy _________ to the digital resources of the library.

A．access

B．passage

C．way

D．approach

目前直接利用太阳能的途径有两种，一种是把太阳能转化为                能，如用集热器把水等物质加热；另一种是把太阳能转化为                 能，如太阳能电池。