阅读下面材料，在空白处填入适当的内容（1个单词）或括号内单词的正确形式。
It’s said that a giant rock was located in the North Sea but once many boats and ships（strike）it and sank．
About a century years ago，a kind and imaginative minister came up with an idea to have a buoy（浮标）（fasten）to the rock．On the top of the buoy（place）a bell，which would ring whenever any ships got closer．When hearing the bell ringing，sailors knew where the rock was and stayed safe．One day，a sea robber Rover happened（sail） not far away from the rock．
Seeing_buoy floating in the water，he decided to play a trick．Soon his crew broke the chain that held the buoy，let the bell go into the water and then sailed away．In the following weeks，they robbed manships around the seas and filled the ship with a great（vary） of treasures．Unfortunately，when returning，they themselves had no idea how to get away from the terrible rock_the ring．The ship was moving swiftly in the darkthere was a great crash．was the very rock  and the ship began to sink．