我们所说的“大豆”，属于以下分类单位中的（　　）

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。

Maybe you always wonder why your pocket money disappeared so quickly. Well, this may be ____you don't have a careful plan. If you try a budget for your pocket money, you will find you can stop money ____ going so fast. A budget is a plan to control where your money ____(go) . Careful budget can help you save for the things you want but can't pay for just now. Useful or not? Look at the ____ (follow) before you start your budget:

● Every month there are things we have to pay for, like school lunches and buses，which are____ (important).There are also things we would like to spend money on — just for fun! All these are ____ (month) expenses (开销).

● Since we can't have money for everything, we have to make ____ (choose). We need to ask if we really need something or just want it. Needs are what you must have in order to live, like food and water. Wants are things you would like to have or do, but not necessary. For example, CDs and cartoons.

● List what you must spend on needs — and if there is money left, you will save for things you really want. This ____ (call) a budget.

● If you don't have enough money for what you need, you may have to give up one for the other. No budget is fixed. Keep an eye on  ____ (you). Maybe you wanted a cartoon book but now you want____ MP3 . Your needs may change into wants, or your wants may change into needs.

材料一　下图为我国铁矿石主要进口来源示意图。

材料二　下图示意1996～2007年我国铁矿石的进口量及均价。

材料三　加工贸易是我国对外贸易的主要方式，但目前我国的加工贸易主要是进行低层次的加工，附加值低。

定义“正对数”：ln⁺x= $\{\begin{array}{c}0,0＜x＜1\\ \ln x,x\ge 1\end{array}$ ，现有四个命题：

①若a＞0，b＞0，则ln⁺（a^b）=bln⁺a；

②若a＞0，b＞0，则ln⁺（ab）=ln⁺a+ln⁺b；

③若a＞0，b＞0，则 ${\ln }^{+}\left(\frac{a}{b}\right)\ge {\ln }^{+}a-{\ln }^{+}b$ ；

④若a＞0，b＞0，则ln⁺（a+b）≤ln⁺a+ln⁺b+ln2．

其中的真命题有____（写出所有真命题的序号）