你想知道今天天气怎样，可以说：          

下列物质由离子直接构成的是（   ）

课外阅读。

一群光头男孩

在印第安纳州的小镇上，有一个名叫布来恩的少年不幸得了脑瘤，他在接受化学治疗。治疗的结果是他漂亮的金发全部掉了。

布来恩难过极了，他整天躲在家里，连最要好的朋友也不见。大家都很着急。

一天，同班的一男孩对自己的妈妈说：“我想把头发全剃光，这样，                                                               。”妈妈赞同地点点头，拿出剃刀，帮儿子把一头（柔软  柔嫩）的金发全剃光了。

这一天，学校里有了一个光头男孩，第二天，学校里又多了一个光头男孩，

第三天，学校里（发现   出现）了一群光头男孩。第四天清早，这一群光头男孩来到布来恩家门口，他们大声叫着布来恩的名字。布来恩透过窗户看到这情景，激动地跑出屋子。这一群光头男孩相拥在一起。每个人都笑得那么欢快。

在暗室中用如图1所示的装置做“测定重力加速度”的实验．

实验器材有：支架、漏斗、橡皮管、尖嘴玻璃管、螺丝夹子、接水铝盒、一根荧光刻度的米尺、频闪仪．

具体实验步骤如下：

①在漏斗内盛满清水，旋松螺丝夹子，水滴会以一定的频率一滴滴地落下．

②用频闪仪发出的白闪光将水滴流照亮，由大到小逐渐调节频闪仪的频率直到第一次看到一串仿佛固定不动的水滴．

③用竖直放置的米尺测得各个水滴所对应的刻度．

④采集数据进行处理

Trip 1  One week in the Mountains
Bring your strong shoes and warm clothes for this walk in a beautiful area of the Green Mountains. You may go hiking or have a try of rock climbing. This is also a protection area for wild animals. You can find many kinds of animals living in this area.
Time: May 8—May 14   Tel: 64639818    Adult: $110     
Trip 2  Three days in the country
There are many beautiful gardens. Take your camera and enjoy the wonderful sight in Hunter Valley. It is a good place for fishing and horse riding. Bird lovers can also enjoy a great walk.
Time: May 20—May 22        Tel: 63986423   Adult: $50      Child: $25
Trip 3  Flashlight adventure
Put on your warm clothes, bring a torch, and come for a night walk along the Dungog Valley. It's a trip full of adventure. A guide will lead the tour. Many of the plants you will see on this trip can only be seen at night.
Time: May 16—May 18     Tel: 63875629      Adult: $30       Not for children
Trip 4  Five days by the sea
Wear your sun hat and enjoy wonderful sunshine all the time from morning to evening. Our hotel is next to the sea. We have our own boats, too. You can swim in the sea or in the swimming pool. Every day our boat will take you to different places for swimming.
Time: May 23—May 27        Tel: 67538293     Adult: $80      Child: $40