A college acquaintance is afraid of train whistles .
一位大学熟人害怕火车汽笛。
In addition to packing lightweight plastic signal mirrors , well-designed whistles and flints that can be used one-handed , each kit contains a special type of tinder called wetfire .
That list , prominently displayed outside venues , also includes whistles , lighters and matches , drink , food in large amounts that can be easily thrown , balls , rackets , frisbees and balloons .
Incremental innovation focuses on making small improvements to existing products and services.it adds a few new bells and whistles , but does not significantly alter the product or the perceived value to the customer .