Нужна помощь! Кому не сложно! complete the following story using the correct forms of the verbs in brackets!

George does not like staying at home when he is on holiday. He … (1) (prefer) going somewhere at the seaside. He … (2) (enjoy) swimming, windsurfing, and diving. Three months ago he was at the Red Sea and when he … (3) (come) back, tanned and happy, he said that he … (4) (never/have) such a terrific holiday before. As he was very good at swimming and diving and was interested in biology, he managed to join a scientific expedition that … (5) (study) the sea life of the Red Sea coast at that time. The researchers … (6) (allow) him to help them in their work and gave him a special suit, for diving, so he … (7) (be able to) stay deep in the sea for quite a long time. George was amazed how beautiful the underwater world was. Millions of brightly coloured fish … (8) (move) busily around him. Crabs, turtles, and sea snakes looked at him curiously and then hurried about their underwater business. Once when George …(9) (follow) a little crab, a huge fish appeared from behind a coral rock. Though he … (10) (never/see) sharks alive, he recoghised it at once. Fortunately, the shark took no interest in him and disappeared intro the depth as if it had much more important things to do.
While George … (11) (work) for the expedition, exploring the sea plants and animals in their natural conditions, he made a firm decision to go on studying biology and natural sciences as the research work … (12) (become) very attractive to him.