用所给词的适当形式填空。 l. He worked hard and has_____ (great) improved his English. 2. My mother always _____ (courage) me to study hard. 3. We all think Nie Haisheng and Fei Junlong are both_____ (hero), 4. Lei Feng's _____ (die) upset everybody. 5. Ba Jin was a great_____ (write).