不是.看主语,and与but连接的句子后面的时态,与主语时态一致.如He likes coffe but dosen't like milk.其中likes和dosen't like都属于一般现在时.又如He ate an apple and drant a cup of tea.其中ate和drank都属于一般过去时.凡是并列连词连接,后面的时态都与前面的时态一致.