Present Perfect образуется при помощи вспомогательного глагола have/has + V3 (глагол в третьей форме). В тексте несколько предложений в данном времени:All the students have brought in a few items from home that are still in good condition.We have decided to do simple things on Buy Nothing Day. We've walked to school instead of taking the bus and we've asked our parents not to go to the supermarket. Present Perfect Continuous образуется при помощи have/has + been + Ving. В тексте одно предложение в данном времени. We have been working hard on it all week.