Name the instruments that are used to measure the following. (i) Length of a soccer field (ii) Things that are not straight (iii) Distance that you have travelled in a vehicle

$$
1 \text{ cm} = 10 \text{ mm} \implies 1 \text{ mm} = \frac{1}{10} \text{ cm}
$$

$$
15 \text{ mm} = 15 \times \frac{1}{10} \text{ cm} = 1.5 \text{ cm}
$$

$$
1 \text{ m} = 100 \text{ cm} \implies 1 \text{ cm} = \frac{1}{100} \text{ m}
$$

$$
1.5 \text{ cm} = 1.5 \times \frac{1}{100} \text{ m} = 0.015 \text{ m}
$$
The conversion is $\boxed{\text{0.015 m}}$.

$$
1 \text{ m} = 100 \text{ cm} \implies 1 \text{ cm} = \frac{1}{100} \text{ m}
$$

$$
28 \text{ cm} = 28 \times \frac{1}{100} \text{ m} = 0.28 \text{ m}
$$

$$
1 \text{ km} = 1000 \text{ m} \implies 1 \text{ m} = \frac{1}{1000} \text{ km}
$$

$$
0.28 \text{ m} = 0.28 \times \frac{1}{1000} \text{ km} = 0.00028 \text{ km}
$$
The conversion is $\boxed{\text{0.00028 km}}$.

$$
1 \text{ km} = 1000 \text{ m}
$$

$$
12 \text{ km} = 12 \times 1000 \text{ m} = 12000 \text{ m}
$$

$$
1 \text{ m} = 100 \text{ cm}
$$

$$
12000 \text{ m} = 12000 \times 100 \text{ cm} = 1200000 \text{ cm}
$$

$$
1 \text{ cm} = 10 \text{ mm}
$$

$$
1200000 \text{ cm} = 1200000 \times 10 \text{ mm} = 12000000 \text{ mm}
$$
The conversion is $\boxed{\text{12000000 mm}}$.