this huge shoal of sardines is shadowed by a ragged tooth shark.这一大群沙丁鱼被一条戟齿砂鮫随尾

a shoal of许多

Shoals of tourists come here in the summer.

这里夏季常有大批游客。

Hundreds have moved into position.数百条鲨鱼就位

move into进入

You may move into the house on completion.

办完手续后，你就可以搬进去。

It's a sixth sense that can give them an edge.鲨鱼靠这种第六感占了上风

six sense第六感

His six sense told him that something was wrong.

他的第六感官告诉他出意外事情了。

they can detect the electrical signals their prey gives off when it moves.可以侦测猎物移动时发出的电讯

give off散发(光、气味等)

Rotten eggs give off a bad smell.

臭蛋散发出难闻的气味。

The flowers gave off a fragrant odor.

花发出一阵幽香。